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Physiology of the Ocular and Cerebrospinal Fluids
BOOK REVIEWS
804
fully trained ophthalmologist will appreciate it very much, for actually it was not written for him. It is excellent for its purpose. Derrick Vail. PHYSIOLOGY
BROSPINAL
OF T H E O C U L A R
FLUIDS.
By
AND CERE-
Hugh
Davson,
D.Sc. Boston, Little, Brown and Com pany, 1956. 388 pages, 109 figures, bibli ography, index. Price: $14.00. One of our leading neurologists has long contended that ophthalmologists are basically neurologists who have made a specialty of cranial nerves I I to V I I and their central connections. That there is much truth in this statement is evidenced by the fact that oph thalmologists have always been intrigued by the similarities between the cerebrospinal fluid and the aqueous humor. W i t h the everincreasing complexity of the physiology of the latter, however, it becomes more and more difficult for the student of ophthalmol ogy to learn all the details of his own fluid, much less his neighbor's. Dr. Davson, how ever, is that rare student, and in this de tailed and comprehensive textbook he demon strates the current pedagogic maxim that much can be learned by abolishing tradi tional departmental lines and allowing fertile minds in different fields to cross-pollinate each other. This book is indeed a sturdy hybrid. The first section is devoted to the ana tomic characteristics of the tissues produc ing the bathing fluids of the eye and central nervous system, and these two chapters are unusually detailed for a textbook of physi ology. There follows a discussion of the composition of the fluids, the mechanisms of production, the nature of the blood-fluid bar rier, and a final section on fluid pressures. The formation of aqueous humor has long been a special love of Dr. Davson's, and this book is essentially a marshalling of the evi dence for his theory of formation of both aqueous and cerebrospinal fluid. H e feels that, in the case of the eye, aqueous is formed first by a special secretory activity of
the cells of the ciliary epithelium and sec ondly by a diffusion of water and salts from the blood vessels of the iris. This is quite at variance with the mechanism proposed by Friedenwald and elaborated by Kinsey, al though the terms secretion and diffusion ap pear in both. H e gives short shrift to the hypotheses developed by these workers. His objections are many, but they center about the fact that in many cases the data for certain substances are not true for all spe cies, that many of the experiments were unphysiologic in regard to the stresses ap plied, and that the theories are too conjec tural for the little data available. F o r exam ple, although Davson agrees that Diamox is a potent agent in decreasing aqueous forma tion by inhibiting the formation of carbonic acid, he feels that the latter may be only one step in the chain of events leading to the formation of the complex substance called aqueous humor rather than the basic mech anism postulated by Friedenwald. It would be unfair not to point out that the late Jonas Friedenwald was well aware that a hypothesis was only a hypothesis and that he always felt that at the moment the particular theory advanced by him gave the best fit for the data available. Some of the data presented by Dr. Davson are equally controversial, and this is all to the good, since in scientific investigation, unlike politi cal investigations, the term "controversial" is stimulating and admirable rather than pe jorative. The bibliography at the end of each chap ter is extensive and brings together in one volume a rather complete survey of the liter ature. David Shoch. S A M U E L GRIDLEY H O W E , SOCIAL R E F O R M E R .
By Harold Schwartz. Cambridge, H a r vard University Press, 1956. 348 pages, bibliography, index. Price: $6.00. O n graduating from H a r v a r d Medical School in 1824, Samuel Gridley Howe, M.D., followed Byron's example and for the
804
fully trained ophthalmologist will appreciate it very much, for actually it was not written for him. It is excellent for its purpose. Derrick Vail. PHYSIOLOGY
BROSPINAL
OF T H E O C U L A R
FLUIDS.
By
AND CERE-
Hugh
Davson,
D.Sc. Boston, Little, Brown and Com pany, 1956. 388 pages, 109 figures, bibli ography, index. Price: $14.00. One of our leading neurologists has long contended that ophthalmologists are basically neurologists who have made a specialty of cranial nerves I I to V I I and their central connections. That there is much truth in this statement is evidenced by the fact that oph thalmologists have always been intrigued by the similarities between the cerebrospinal fluid and the aqueous humor. W i t h the everincreasing complexity of the physiology of the latter, however, it becomes more and more difficult for the student of ophthalmol ogy to learn all the details of his own fluid, much less his neighbor's. Dr. Davson, how ever, is that rare student, and in this de tailed and comprehensive textbook he demon strates the current pedagogic maxim that much can be learned by abolishing tradi tional departmental lines and allowing fertile minds in different fields to cross-pollinate each other. This book is indeed a sturdy hybrid. The first section is devoted to the ana tomic characteristics of the tissues produc ing the bathing fluids of the eye and central nervous system, and these two chapters are unusually detailed for a textbook of physi ology. There follows a discussion of the composition of the fluids, the mechanisms of production, the nature of the blood-fluid bar rier, and a final section on fluid pressures. The formation of aqueous humor has long been a special love of Dr. Davson's, and this book is essentially a marshalling of the evi dence for his theory of formation of both aqueous and cerebrospinal fluid. H e feels that, in the case of the eye, aqueous is formed first by a special secretory activity of
the cells of the ciliary epithelium and sec ondly by a diffusion of water and salts from the blood vessels of the iris. This is quite at variance with the mechanism proposed by Friedenwald and elaborated by Kinsey, al though the terms secretion and diffusion ap pear in both. H e gives short shrift to the hypotheses developed by these workers. His objections are many, but they center about the fact that in many cases the data for certain substances are not true for all spe cies, that many of the experiments were unphysiologic in regard to the stresses ap plied, and that the theories are too conjec tural for the little data available. F o r exam ple, although Davson agrees that Diamox is a potent agent in decreasing aqueous forma tion by inhibiting the formation of carbonic acid, he feels that the latter may be only one step in the chain of events leading to the formation of the complex substance called aqueous humor rather than the basic mech anism postulated by Friedenwald. It would be unfair not to point out that the late Jonas Friedenwald was well aware that a hypothesis was only a hypothesis and that he always felt that at the moment the particular theory advanced by him gave the best fit for the data available. Some of the data presented by Dr. Davson are equally controversial, and this is all to the good, since in scientific investigation, unlike politi cal investigations, the term "controversial" is stimulating and admirable rather than pe jorative. The bibliography at the end of each chap ter is extensive and brings together in one volume a rather complete survey of the liter ature. David Shoch. S A M U E L GRIDLEY H O W E , SOCIAL R E F O R M E R .
By Harold Schwartz. Cambridge, H a r vard University Press, 1956. 348 pages, bibliography, index. Price: $6.00. O n graduating from H a r v a r d Medical School in 1824, Samuel Gridley Howe, M.D., followed Byron's example and for the