DISCOVERY 



S3 



at the Court and with the assistance of the Caliph 

 Muta-Wahkil. (a.d. 847-861.) By 'Ali Tabari. 

 Translated b)- A. Mingana, D.D. (Manchester 

 University Press, Longmans, Gr;en & Co., and 

 Bernard Quaritch, Ltd., los. 6d.) 



The Outline of History. By H. G. Wells. The Defini- 

 tive Edition. Revised and rearranged by tlie 

 Author. (Cassell & Co., Ltd., ai.';.) 



PSYCHOLOGY 



Conditions of Nervous Anxiety and their Treatment. By 

 \V. Stekel. Authorised translation by Rosalie 

 G.\BLER. (Kegan Paul, Trench, Triibner & Co., 

 Ltd., 25s.) 



An Introduction to the Psychology of Religion. By Robert 

 H. Thouless, M.A. (Cambridge University Press, 

 75. 6if.) 



Psychology and Politics. By W. H. R. Rivers, LL.D., 

 F.R.S., etc. With Notes by G. Elliot S.mith. F.R.S., 

 and C. S. Myers, F.R.S. (Kegan Paul, Trench, 

 Triibner & Co., Ltd. ,125. 6J ) 



Conflict and Dream. By W. H. R. Rivers, LL.D., 

 F.R.S., etc. With Preface by G. Elliot Smith, 

 F.R.S. (Kegan Paul, Trench, Triibner & Co., 

 Ltd., I2S. 6d.) 



SCIENXE 



On Certain Pathological Elements in Human Blood. By 

 C. H. Collings. 



Glands in Health and Disease. By Benjamin Harrow, 

 Ph.D. (George Routledge & Sons, Ltd., 8s. 6d.) 



Biology for Beginners. By Truman J. Moon. (George 

 G. Harrap & Co., 6s.) 



A very complete survey of Biology, up-to-date and 

 fully illustrated. Although intended for schools, it will 

 be welcomed by many whose interest in natural history 

 is neither compulsory nor utilitarian. The price, when 

 the scope, the numerous illustrations and the wide appeal 

 of this carefully written book are considered, is sur- 

 prisingly low. One feature, however, deserves comment. 

 The author concludes with a terrible denunciation of 

 alcohol and tobacco — " Tobacco decreases your personal 

 attractiveness. The odour of breath, hands, and per- 

 spiration, the stains on fingers and teeth, do not add to 

 your good looks." Tea "sometimes seems to soothe the 

 nerves (which ought not to need soothing)." The book 

 hails from America, and the picture of a biology class 

 studying the tobacco craze calls up surmises of New York 

 classical students at their tasks. Do they, we wonder, 

 discuss chewing gum ? 



A Textbook of Inorganic Chemistry. By G. S. Newth, 

 F.LC, F.C.S. (Longmans, Green & Co., 8s.) 



A new and enlarged edition for 1923 of a long-estab- 

 lished and much-used book. 



Correspondence 



THE DEGENERATION OF FUNCTIONLESS 

 ORGANS 



Sir, 



To the Editor of Discovery 



I have been recently much interested in the 

 phenomena of atrophy and degeneration. The subject 

 is a very debatable one, but, although discussed at 

 length in all works on heredity and evolution, I have 

 never seen any reference to the explanation that I now 

 put forward, and it is on that account that I hope you 

 will find room for this letter in the pages of your excellent 

 journal. 



My attention was first attracted to the subject by the 

 weakness of the unsatisfactory explanation to which all 

 the authors on the subject seem to be forced. Take first 

 the case of the abortive wings of certain species of birds 

 which, throughout many generations, have ceased to 

 fly. Most authors strive to explain this on the principles 

 of Natural Selection, saying that those individuals, having 

 an inborn smallness of wing, were able to develop greater 

 leg power and thus tended to be preserved. So far so 

 good, but, as Mr. Watson points out, " In certain cases such 

 an explanation seems undeniably far-fetched. Take the 

 case of the abortive eyes of cave-dweUing fishes." Here 

 then the Natural Selection solution of the problem seems 

 to break down and Mr. Watson, and indeed all other 

 authors on the subject, are forced to the rather weak 

 conclusion that " the inheritance of the effects of disuse 

 is the obvious e.xplanation, and any other must appear 

 both less simple and less probable." 



I say that this conclusion is weak because these same 

 authors express disbelief in the uncertain and, indeed, 

 almost certainly imaginary phenomenon of the inheritance 

 of acquired characters. Yet tins explanation necessitates 

 a slight acknowledgment of the validity of the pheno- 

 menon, for eye-weakness produced by life in the dark is 

 a character acquired after the body- and germ-plasms 

 have become separate. Many biologists have tried to 

 explain away this contradiction by saying that mutila- 

 tions have only a slight effect on the general system and 

 are not, therefore, inherited, but the effects of disuse 

 burrow deeper and are likely to affect the germ-cells. 

 This does not appear to me to be a solution, but rather 

 an admission of failure to solve. In the first place, the 

 truth of the statement is debatable ; secondly, even if 

 we assume it true, why should the disuse of an organ 

 aftect only that portion of the germ-plasm representing 

 it, unless we resurrect a theory like the Pangenesis of 

 Darwin — surely the most complicated and least probable 

 theory ever propounded ? 



None of these biologists seem to have looked for an 

 explanation in the better-known and more certain process 

 of Natural Selection. Why not ? They seem to regard 

 Natural Selection as a process of elimination only ; but 

 why not also a process of retention ? To take the case 

 of the fishes already mentioned. Fish living in the light 

 are dependent on their sight for their safety ; conse- 

 quently Natural Selection has eliminated those indi\'iduals 



