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The Durability of a Glass Substitute
THE DURABILITY OF A GLASS SUBSTITUTE WALTER C. RUSSELL, AND C. H. HOWARD* From the Department of Agricultural Biochemistry, New Jersey Agricultural Experiment Station, New Brunswick, New Jersey
* Cel-O-Glass Industrial Fellow. This investigation was conducted under a fellowship grant from Acetol Products, Inc., New York.
290
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(Received for Publication 2-9-29) It has beeen well established by Hart and Steenbock and their associates,1 Hughes, 2 Murray, Little and Bovie,3 and Bethke, Kennard and Kik4 that direct sunlight will prevent leg weakness and promote bone formation in young chicks, whereas control groups on the same ration but kept out of direct sunlight develop leg weakness and death ensues in many eases. The work of Murray, Little and Bovie,3 Wood,5 the Council on Physical Therapy of the American Medical Association6, and of Bethke and Kennard 7 gives ample demonstration that ordinary window glass does not transmit the rays of sunlight which are effective in the preventing of leg weakness and in the promotion of normal skeletal formation in young chicks on a ration deficient in the antirachitic factor. Hence it has been concluded that the ultraviolet portion of the sun's radiation shorter than about 3200A, the lower limit of transmission by window glass, is responsible for the difference. The observations of several of the above mentioned investigators (1), (2), (3), and of many others that an artificial source of ultraviolet rays, whose spectrum includes those shorter than 3200A, promotes the formation of skeletal tissue and prevents leg weakness in growing chicks have given further confirmation to the conclusion that it is the rays shorter than those transmitted by window glass that are effective. Such findings have led to the development of materials designed to transmit the effective ultraviolet rays of sunlight and to afford the same protection against weather conditions as common window glass does. Materials possessing these properties would be of value to the poultryman rearing young stock in confinement during the colder months of the year. To be economically practical the material would have to be sufficiently durable to withstand weather conditions, and not decrease so markedly in ultraviolet-transmitting ability with weathering and exposure to solar rays that it fails to pass enough of the active
GLASS
SUBSTITUTE
291
EXPERIMENTAL
PROCEDURE
The conduct of the experiment and the analytical procedure were essentially as outlined in a previous publication. 8 A group of 300 7-day old White Leghorn chicks was divided into 3 lots of 100 each, so that the weight distribution of the original lot was represented in each. During the pre-experimental period and throughout the experiment, the ration offered was that used in an earlier experiment. 8 I t consisted of 99 parts of yellow corn plus 1 part sodium chloride and liquid skimmed milk, both foods being offered ad libitum. 9 Prior to the experimental period the birds were housed in a basement laboratory in the absence of direct sunlight. For experimental purposes Lot 1 was placed in a 9 x 1 2 poultry house, the south wall of which was constructed of new Cel-OGlass. The area of the wall was 9'6" x 5'6". Lot 2 was confined in a house with a specially constructed window of the glass substitute, Cel-O-Glass, which was a quarter section of a cone, having a southern exposure. A small area of the vertical walls was also covered with the glass substitute. The material of this window was placed on the house in early January, 1927, used in an experiment reported by Russell and Massengale8 and allowed to remain on the house to be used for the present experiment. In the earlier experiment 8 it was demonstrated that the winter sun-
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rays to supply the requirements of the animal organism. In the study of these materials it is essential to determine whether their efficiency decreases with weathering and aging. The primary object of this investigation was to determine whether 1 3 ^ months of continuous exposure to weather conditions had decreased the efficiency of the glass substitute under examination for the transmission of the physiologically active ultra-violet rays. In addition to the test of the effect of weathering on the glass substitute another experiment was conducted at the same time, the object of which was to determine the effectiveness of the ultraviolet rays of the sunlight of the latter part of February, March and April which had passed through a new sample.of the glass substitute, used as the south wall of a practical poultry house. The results of this experiment are also used for comparison with those obtained with the material which had been exposed to the weather.
292
POULTRY
SCIENCE
ANALYTICAL METHODS
Ten individuals were selected each week from Lots 1 and 2 and four times during the experiment from Lot 3 for bone ash determinations. The sampling was done so that the weight distribution of the selected lot was the same as that of the whole.s Ash determinations of the pooled femurs (Os femoris) and of the large wing bones (Humerus) were made according to the method described in a previous publication. 8 In order to test the validity of the analytical data obtained in this kind of work and used for the determination of a point on a bone ash-time curve, a statistical study 10 was made of results of earlier experiments. In each of thirty cases an average of the individual bone ash percentages of the femurs of 6 individuals was used to determine a point. A calculation of the probable error as the percentage of its mean was made for each case. The average probable error for the 30 cases was ± 0.80% of the mean of any one of them, with a range between 0.43% and 1.45%. The use of 10 individuals, as was the practice in the present investigation, would probably reduce the size of the probable error.
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light of January, February, and early March, 1927, which had passed through the glass substitute was effective in the prevention of leg weakness and in the promotion of what is probably normal bone formation for the ration used, in chicks up to 11 weeks of age. After lZ1^ months the material had w.eathered slightly and had become somewhat opaque, but it was still satisfactory for the protection of young chicks against the weather and, as the results presented below indicate, permitted the passage of sufficient of the ultraviolet rays. The continuous exposure conditions to which the material was subjected were more severe than those of practical use, because in actual practice the period of use is only those months during which stock requires protection against the weather. Lot 3 was kept as a control group in a basement laboratory and out of contact with direct sunlight. The birds of Lots 1 and 2 were exposed to the ultraviolet, rays of the sun for the first time at 7 days of age and were allowed as much of the sun's radiation as passed through the glass substitute. The experimental period was from February 15, 1928 until April 17, 1928.
GLASS SUBSTITUTE
293
DISCUSSION OF RESULTS
Curve 1, Fig. 1, reproduced from an earlier experiment, 8 shows the result obtained when chicks of the same age as those of this experiment and on the same ration were given 20 minutes per day of ultraviolet radiations from a quartz mercury lamp at a distance of three feet. The response to the 20 minute exposure was practically the same as that of a 15 minute ex«J7|
1
1
r—i
1
1
I
I —
I
1
1
;
1
1
i—i
1
1
,
•w
1
1 .
—
Wwks o^ E x p e r i m e n t
PIG. 1. Percentage ash of thigh bones (Os femoris). Curve 1, 20 minutes per day of ultraviolet radiations from a quartz mercury lamp at a distance of 3 feet. Curve 2, sunlight through the glass substitute when new in 1927. Curve 3, sunlight through the glass substitute after exposure to the weather for 13% months. Curve 4, sunlight through the glass substitute, when new in 1928. Curve 5, no exposure to ultra-violet light.
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J3
294
POULTRY
SCIENCE
38 37
;
3&
3S] o
.
1
1 l
1
1 Z
1
1 3
1
L 1 1 1 1 1 + •f 6 W « « k s o§ E x p e r i m e n t .
1 7
1
1 a
1
1 3
1
FIG. 2. Percentage ash of wing bones (Humerus). Curves 1 to 4 same as for Fig. 1.
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posure. Although the mineral content of the ration may have been a limiting factor, Curve 1 is considered as a probably normal curve for the ration used. Curve 5, Fig. 1, gives ample demonstration that the ration was deficient in the antirachitic factor and confirms several previous trials with this ration. Curve 2, Fig. 1, is reproduced from the report 8 of the experiment conducted in January, February and early March, 1927, and is to be compared with Curve 3 which was obtained with the same sample of the glass substitute, after lBy2 months of exposure to weather conditions. Although the trend of Curve 3, Fig. 1, is a little higher than that of Curve 2, the difference is not considered significant. The 1928 experiment was begun
GLASS
SUBSTITUTE
295
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about 6 weeks later, February 15, than that of 1927, which was started on January 5. The intensity and amount of ultraviolet radiations during the period of the 1928 experiment would be greater than that of the 1927 trial, but the difference between the two periods would probably not be sufficient to account for the results obtained with the weathered material, if the efficiency of transmission had decreased markedly. It is quite possible that the material when new transmitted much more of the radiant energy of the sun than that required by the animal organism and that the weathering has caused a decrease in transmitting ability. Any decrease, however, has not been sufficient to inhibit the promotion of bone formation in the chicken. Curve 4, Fig. 1, shows the response obtained with Lot 1 when new material was used as the vertical south wall of a practical poultry house instead of as the surface of a quarter section of a cone, as in the case of Lot 2. In considering the effects of weathering it should be noted that this curve has practically the same trend as that of the 1927 experiment (Curve 2) and of Lot 2 (Curve 3) of the 1928 experiment. Hence the response under the weathered material was equal to that under the new material, the two experiments having been conducted under identical seasonal conditions. The curves of Figure 2, those of the wing bone, bear the same relationship to each other as those of Figure 1. The maximum values reached by these curves are higher than those of the femurs as has been our experience in the past. The curves are presented in confirmation of the values obtained by analysis of the femurs. In addition to the biological test a spectrographic comparison was made of the percentage transmission of the weathered with new material, employing the photometric method. The weathered sample was taken from the house after 24 months of continuous exposure and 8% months after the completion of the 1928 experiment. The sample was from the vertical wall because the material which covered the cone-shaped portion was badly weathered after 2 years of continuous exposure. The length and conditions of the exposure, it should be noted, were far more rigorous than the material would receive in practical
296
POULTRY
SCIENCE
use. Following are the results of the spectrographic measurements.! TABLE I.—SPECTKOGSAPHIC MEASUREMENTS. Condition of the Material Percentage Transmission 3000 A 3100 A 3200 A per cent per cent per cent
New After 24 m o n t h s of continuous exposure to w e a t h e r conditions
33
48
63
25
31
46
SUMMARY
1. The rays of winter and early spring sunlight, which have to do with the prevention of leg weakness and the promotion of bone formation, were transmitted by a sample of the glass substitute, Cel-O-Glass, used after 13% months of exposure to weather conditions, in an amount sufficient to produce the same effect with reference to bone formation as when the material was new. 2. The sunlight of the period, February 15—April 17, 1928, at New Brunswick, New Jersey, (about 40°30'N., 32 miles southeast of New York City) after passage through a new sample of the glass substitute, used as the vertical, south wall of a poultry house, was found to be sufficiently potent in the rays which have to do with the formation of skeletal tissue and the prevention of leg weakness. 3. Spectrographic measurements, made at a later date than the termination of the biological test, show a decrease in the percentage transmission with weathering, but the amount of any decrease which had taken place previous to the biological test was not sufficient to cause the degree of bone formation to be less than that which had been obtained with new material. f The m e a s u r e m e n t s were made in t h e D e p a r t m e n t of Physics, Rutgers University.
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In view of the results of the biological test any decrease in percentage transmission, which had taken place previous to the test, was not sufficient to diminish the extent of bone formation in the young chick, which was obtained when the material was new. Further biological and spectrographic tests are to be made of material which has had several seasons of use on a practical poultry house.
GLASS
SUBSTITUTE
297
BIBLIOGRAPHY i HART, E. B., STEENBOCK, H.,
LEPKOVSKY, S., AND H A L P I N , J.
G.,
J.
Biol. Chem., (1923), lviii, 33. 2 H U G H E S , J. S., Science, 1924, lix, 213; POULTRY SCI., 1925, iv, .151.
s MURRAY, J. M., LITTLE, C. C , AND BOVIE, W. T., Maine Agric. E x p t .
Sta. Bull., 320, Dec. 1924. * B E T H K E , R. M., KENNARD, D. C , AND K I K , M. C , J. Biol. Chem., 1925,
lxiii, 377. s WOOD, J R . , W. F., POULTRY S C I . , 1927, vi, 62.
e Council on Physical Therapy, American Medical Association, J. Amer. Med. A s s o c , 1927, lxxxviii, 1562. s R U S S E L L , W . C. AND MASSENGALE, 0 . N., POULTRY SCIENCE, 1928,
vii,
85. s> Wisconsin Agric. Expt. Sta. Bull. 371, 21 (1925). io SHERMAN, Chemistry of Food a n d Nutrition, p. 605, New York, 1926. J o u r n a l Series paper of t h e New Jersey A g r i c u l t u r a l E x p e r i m e n t Station, D e p a r t m e n t of A g r i c u l t u r a l Biochemistry.
Downloaded from http://ps.oxfordjournals.org/ at NERL on May 11, 2015
i B E T H K E , R. M. AND KENNARD, D. C , POULTRY SCI., vi, 290.
* Cel-O-Glass Industrial Fellow. This investigation was conducted under a fellowship grant from Acetol Products, Inc., New York.
290
Downloaded from http://ps.oxfordjournals.org/ at NERL on May 11, 2015
(Received for Publication 2-9-29) It has beeen well established by Hart and Steenbock and their associates,1 Hughes, 2 Murray, Little and Bovie,3 and Bethke, Kennard and Kik4 that direct sunlight will prevent leg weakness and promote bone formation in young chicks, whereas control groups on the same ration but kept out of direct sunlight develop leg weakness and death ensues in many eases. The work of Murray, Little and Bovie,3 Wood,5 the Council on Physical Therapy of the American Medical Association6, and of Bethke and Kennard 7 gives ample demonstration that ordinary window glass does not transmit the rays of sunlight which are effective in the preventing of leg weakness and in the promotion of normal skeletal formation in young chicks on a ration deficient in the antirachitic factor. Hence it has been concluded that the ultraviolet portion of the sun's radiation shorter than about 3200A, the lower limit of transmission by window glass, is responsible for the difference. The observations of several of the above mentioned investigators (1), (2), (3), and of many others that an artificial source of ultraviolet rays, whose spectrum includes those shorter than 3200A, promotes the formation of skeletal tissue and prevents leg weakness in growing chicks have given further confirmation to the conclusion that it is the rays shorter than those transmitted by window glass that are effective. Such findings have led to the development of materials designed to transmit the effective ultraviolet rays of sunlight and to afford the same protection against weather conditions as common window glass does. Materials possessing these properties would be of value to the poultryman rearing young stock in confinement during the colder months of the year. To be economically practical the material would have to be sufficiently durable to withstand weather conditions, and not decrease so markedly in ultraviolet-transmitting ability with weathering and exposure to solar rays that it fails to pass enough of the active
GLASS
SUBSTITUTE
291
EXPERIMENTAL
PROCEDURE
The conduct of the experiment and the analytical procedure were essentially as outlined in a previous publication. 8 A group of 300 7-day old White Leghorn chicks was divided into 3 lots of 100 each, so that the weight distribution of the original lot was represented in each. During the pre-experimental period and throughout the experiment, the ration offered was that used in an earlier experiment. 8 I t consisted of 99 parts of yellow corn plus 1 part sodium chloride and liquid skimmed milk, both foods being offered ad libitum. 9 Prior to the experimental period the birds were housed in a basement laboratory in the absence of direct sunlight. For experimental purposes Lot 1 was placed in a 9 x 1 2 poultry house, the south wall of which was constructed of new Cel-OGlass. The area of the wall was 9'6" x 5'6". Lot 2 was confined in a house with a specially constructed window of the glass substitute, Cel-O-Glass, which was a quarter section of a cone, having a southern exposure. A small area of the vertical walls was also covered with the glass substitute. The material of this window was placed on the house in early January, 1927, used in an experiment reported by Russell and Massengale8 and allowed to remain on the house to be used for the present experiment. In the earlier experiment 8 it was demonstrated that the winter sun-
Downloaded from http://ps.oxfordjournals.org/ at NERL on May 11, 2015
rays to supply the requirements of the animal organism. In the study of these materials it is essential to determine whether their efficiency decreases with weathering and aging. The primary object of this investigation was to determine whether 1 3 ^ months of continuous exposure to weather conditions had decreased the efficiency of the glass substitute under examination for the transmission of the physiologically active ultra-violet rays. In addition to the test of the effect of weathering on the glass substitute another experiment was conducted at the same time, the object of which was to determine the effectiveness of the ultraviolet rays of the sunlight of the latter part of February, March and April which had passed through a new sample.of the glass substitute, used as the south wall of a practical poultry house. The results of this experiment are also used for comparison with those obtained with the material which had been exposed to the weather.
292
POULTRY
SCIENCE
ANALYTICAL METHODS
Ten individuals were selected each week from Lots 1 and 2 and four times during the experiment from Lot 3 for bone ash determinations. The sampling was done so that the weight distribution of the selected lot was the same as that of the whole.s Ash determinations of the pooled femurs (Os femoris) and of the large wing bones (Humerus) were made according to the method described in a previous publication. 8 In order to test the validity of the analytical data obtained in this kind of work and used for the determination of a point on a bone ash-time curve, a statistical study 10 was made of results of earlier experiments. In each of thirty cases an average of the individual bone ash percentages of the femurs of 6 individuals was used to determine a point. A calculation of the probable error as the percentage of its mean was made for each case. The average probable error for the 30 cases was ± 0.80% of the mean of any one of them, with a range between 0.43% and 1.45%. The use of 10 individuals, as was the practice in the present investigation, would probably reduce the size of the probable error.
Downloaded from http://ps.oxfordjournals.org/ at NERL on May 11, 2015
light of January, February, and early March, 1927, which had passed through the glass substitute was effective in the prevention of leg weakness and in the promotion of what is probably normal bone formation for the ration used, in chicks up to 11 weeks of age. After lZ1^ months the material had w.eathered slightly and had become somewhat opaque, but it was still satisfactory for the protection of young chicks against the weather and, as the results presented below indicate, permitted the passage of sufficient of the ultraviolet rays. The continuous exposure conditions to which the material was subjected were more severe than those of practical use, because in actual practice the period of use is only those months during which stock requires protection against the weather. Lot 3 was kept as a control group in a basement laboratory and out of contact with direct sunlight. The birds of Lots 1 and 2 were exposed to the ultraviolet, rays of the sun for the first time at 7 days of age and were allowed as much of the sun's radiation as passed through the glass substitute. The experimental period was from February 15, 1928 until April 17, 1928.
GLASS SUBSTITUTE
293
DISCUSSION OF RESULTS
Curve 1, Fig. 1, reproduced from an earlier experiment, 8 shows the result obtained when chicks of the same age as those of this experiment and on the same ration were given 20 minutes per day of ultraviolet radiations from a quartz mercury lamp at a distance of three feet. The response to the 20 minute exposure was practically the same as that of a 15 minute ex«J7|
1
1
r—i
1
1
I
I —
I
1
1
;
1
1
i—i
1
1
,
•w
1
1 .
—
Wwks o^ E x p e r i m e n t
PIG. 1. Percentage ash of thigh bones (Os femoris). Curve 1, 20 minutes per day of ultraviolet radiations from a quartz mercury lamp at a distance of 3 feet. Curve 2, sunlight through the glass substitute when new in 1927. Curve 3, sunlight through the glass substitute after exposure to the weather for 13% months. Curve 4, sunlight through the glass substitute, when new in 1928. Curve 5, no exposure to ultra-violet light.
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J3
294
POULTRY
SCIENCE
38 37
;
3&
3S] o
.
1
1 l
1
1 Z
1
1 3
1
L 1 1 1 1 1 + •f 6 W « « k s o§ E x p e r i m e n t .
1 7
1
1 a
1
1 3
1
FIG. 2. Percentage ash of wing bones (Humerus). Curves 1 to 4 same as for Fig. 1.
Downloaded from http://ps.oxfordjournals.org/ at NERL on May 11, 2015
posure. Although the mineral content of the ration may have been a limiting factor, Curve 1 is considered as a probably normal curve for the ration used. Curve 5, Fig. 1, gives ample demonstration that the ration was deficient in the antirachitic factor and confirms several previous trials with this ration. Curve 2, Fig. 1, is reproduced from the report 8 of the experiment conducted in January, February and early March, 1927, and is to be compared with Curve 3 which was obtained with the same sample of the glass substitute, after lBy2 months of exposure to weather conditions. Although the trend of Curve 3, Fig. 1, is a little higher than that of Curve 2, the difference is not considered significant. The 1928 experiment was begun
GLASS
SUBSTITUTE
295
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about 6 weeks later, February 15, than that of 1927, which was started on January 5. The intensity and amount of ultraviolet radiations during the period of the 1928 experiment would be greater than that of the 1927 trial, but the difference between the two periods would probably not be sufficient to account for the results obtained with the weathered material, if the efficiency of transmission had decreased markedly. It is quite possible that the material when new transmitted much more of the radiant energy of the sun than that required by the animal organism and that the weathering has caused a decrease in transmitting ability. Any decrease, however, has not been sufficient to inhibit the promotion of bone formation in the chicken. Curve 4, Fig. 1, shows the response obtained with Lot 1 when new material was used as the vertical south wall of a practical poultry house instead of as the surface of a quarter section of a cone, as in the case of Lot 2. In considering the effects of weathering it should be noted that this curve has practically the same trend as that of the 1927 experiment (Curve 2) and of Lot 2 (Curve 3) of the 1928 experiment. Hence the response under the weathered material was equal to that under the new material, the two experiments having been conducted under identical seasonal conditions. The curves of Figure 2, those of the wing bone, bear the same relationship to each other as those of Figure 1. The maximum values reached by these curves are higher than those of the femurs as has been our experience in the past. The curves are presented in confirmation of the values obtained by analysis of the femurs. In addition to the biological test a spectrographic comparison was made of the percentage transmission of the weathered with new material, employing the photometric method. The weathered sample was taken from the house after 24 months of continuous exposure and 8% months after the completion of the 1928 experiment. The sample was from the vertical wall because the material which covered the cone-shaped portion was badly weathered after 2 years of continuous exposure. The length and conditions of the exposure, it should be noted, were far more rigorous than the material would receive in practical
296
POULTRY
SCIENCE
use. Following are the results of the spectrographic measurements.! TABLE I.—SPECTKOGSAPHIC MEASUREMENTS. Condition of the Material Percentage Transmission 3000 A 3100 A 3200 A per cent per cent per cent
New After 24 m o n t h s of continuous exposure to w e a t h e r conditions
33
48
63
25
31
46
SUMMARY
1. The rays of winter and early spring sunlight, which have to do with the prevention of leg weakness and the promotion of bone formation, were transmitted by a sample of the glass substitute, Cel-O-Glass, used after 13% months of exposure to weather conditions, in an amount sufficient to produce the same effect with reference to bone formation as when the material was new. 2. The sunlight of the period, February 15—April 17, 1928, at New Brunswick, New Jersey, (about 40°30'N., 32 miles southeast of New York City) after passage through a new sample of the glass substitute, used as the vertical, south wall of a poultry house, was found to be sufficiently potent in the rays which have to do with the formation of skeletal tissue and the prevention of leg weakness. 3. Spectrographic measurements, made at a later date than the termination of the biological test, show a decrease in the percentage transmission with weathering, but the amount of any decrease which had taken place previous to the biological test was not sufficient to cause the degree of bone formation to be less than that which had been obtained with new material. f The m e a s u r e m e n t s were made in t h e D e p a r t m e n t of Physics, Rutgers University.
Downloaded from http://ps.oxfordjournals.org/ at NERL on May 11, 2015
In view of the results of the biological test any decrease in percentage transmission, which had taken place previous to the test, was not sufficient to diminish the extent of bone formation in the young chick, which was obtained when the material was new. Further biological and spectrographic tests are to be made of material which has had several seasons of use on a practical poultry house.
GLASS
SUBSTITUTE
297
BIBLIOGRAPHY i HART, E. B., STEENBOCK, H.,
LEPKOVSKY, S., AND H A L P I N , J.
G.,
J.
Biol. Chem., (1923), lviii, 33. 2 H U G H E S , J. S., Science, 1924, lix, 213; POULTRY SCI., 1925, iv, .151.
s MURRAY, J. M., LITTLE, C. C , AND BOVIE, W. T., Maine Agric. E x p t .
Sta. Bull., 320, Dec. 1924. * B E T H K E , R. M., KENNARD, D. C , AND K I K , M. C , J. Biol. Chem., 1925,
lxiii, 377. s WOOD, J R . , W. F., POULTRY S C I . , 1927, vi, 62.
e Council on Physical Therapy, American Medical Association, J. Amer. Med. A s s o c , 1927, lxxxviii, 1562. s R U S S E L L , W . C. AND MASSENGALE, 0 . N., POULTRY SCIENCE, 1928,
vii,
85. s> Wisconsin Agric. Expt. Sta. Bull. 371, 21 (1925). io SHERMAN, Chemistry of Food a n d Nutrition, p. 605, New York, 1926. J o u r n a l Series paper of t h e New Jersey A g r i c u l t u r a l E x p e r i m e n t Station, D e p a r t m e n t of A g r i c u l t u r a l Biochemistry.
Downloaded from http://ps.oxfordjournals.org/ at NERL on May 11, 2015
i B E T H K E , R. M. AND KENNARD, D. C , POULTRY SCI., vi, 290.