REPRODUCTION. 497 



parental somatoplasm capable of inducing such changes in the germ-plasm thai 

 somatic peculiarities appear in the offspring similar to those possessed by the 

 parent? Weismann classifies all somatic variations according to their origin 

 into three groups — viz. injuries, functional variations, and variations, mainly 

 climatic, that depend upon the environment. The problem of their inherit- 

 ance is a far-reaching one, and upon its correct solution depend principles that 

 are of much wider application than simply to matters of heredity ; for if 

 acquired characters can be inherited, there is revealed to us a most potent fac- 

 tor in the transformation of species, and the whole question of the possibility 

 of use and disuse as factors of evolution is presented. The larger evolutionary 

 problem need not here be considered. 



Regarding the problem of the inheritance of acquired characteristics we may 

 say at once that it is not yet solved. To the lay mind this may seem strange, 

 for at first thought it appears self-evident that parents may transmit to their 

 children peculiarities that they themselves have acquired. Affirmative evidence 

 seems all about us, as witness the undoubted cases of inheritance of artistic 

 tastes, of talent, of traits valuable in professional life, which seem to originate 

 in the industry of the parent. But scientific analysis by Weismann and others 

 of popular impressions, popular anecdotes and hearsay evidence, and accurate 

 original observation, have revealed little that cannot as well be explained on 

 other hypotheses. Anatomical and functional peculiarities of the body that are 

 apparently new often reappear in successive generations, but to assume that 

 they are acquired by the somatoplasm and have become congenital, rather than 

 that they are germinal from the first, is unwarranted. Direct experiments by 

 various investigators are almost as inconclusive. Weismann ' has removed the 

 tails of white mice for five successive generations, and yet of 901 young every 

 individual was born with a tail normal in length and in other respects. Bos 2 

 has experimented similarly upon rats for ten generations without observing any 

 diminution of the tails. The practice of circumcision for centuries has resulted 

 in no reduction of the prepuce. The binding of the feet of Chinese girls has 

 not resulted in any congenital malformation of the Chinese foot. Brown- 

 Sequard, 3 and later Obersteiner, 4 have artificially produced epilepsy in guinea- 

 pigs by various operations upon the central nervous system and the peripheral 

 nerves, and the offspring of such parents have been epileptic. At first this 

 would seem to amount to proof of the actual hereditary transmission <»(* mutila- 

 tions, yet in these eases the mutilation itself was not transmitted ; the offspring 

 were weak and sickly and exhibited a variety of abnormal nervous and nutri- 

 tional symptoms, among which was a tendency Inward epileptiform convulsions, 

 the cause of which is still to be explained. Evidence from palaeontology 

 regarding the apparent gradual accumulation of the effects of use ami disuse 

 throughout a long-continued animal series seems to require the assumption of 



1 A. Weismann : Essays upon Heredity, vol. L, L889, p. 432. 



* J. R. Bos: Biologisches Centmlblatt, xi., 1891, S. 7:11. 



3 E. Brown S('i|ii:u(l : Researches on Epilepsy, ''<•.. Boston, 1857; also various later papers. 



4 H. Obersteiner : Medizmische Jahrbiicher, Wien L875, S. 17'.'. 



Vol. IT.— 32 



