352 PRESENT PROBLEMS IN EVOLUTION AND HEREDITY. 



Orustein report affirmative cases. His shows that an affirmative case, 

 cited by V. Zwieciki, is merely an inherited pecnliarity. Tlie entire 

 evidence is unsatisfactory, and upon tlie whole, is decidedly negative. 



Not so however in cases where the mutilation results in a general 

 disturbance of the normal functions of different organs, as in the ex- 

 l)eriments conducted by BrownSequard* upon guinea-pigs, in which 

 we see "acquired variation" intensified. In these, abnormal degener- 

 ation of the toes, nmscular atrophy of the thigh, epilepsy, exophthal- 

 inia, etc., appeared in the descendants of animals in which the spinal 

 cord or sciatic nerve had been severed, or portions of the brain removed. 

 It was also shown that the fenmleismore apt to transmit morbid states 

 than the male; that the inheritance of thel^e injuries may i)ass over 

 one generation and re-appear in the second ; that the transmission by 

 heredity of these pathological results may continue for five or six gen- 

 erations, when the normal structure of the organs re-appears. These 

 cases, wiiich are incontestable, at first sight appear to establish flrndy 

 the transmission of acquired characters; they were so regarded by 

 Brown-Sequard. These lesions act directly ui)on the organs, and the 

 abiiormal growth of these organs appears to be transmitted. But can 

 they not be interpreted in another way, namely, that the pathological 

 condition of the nerve centers has induced a direct disturbance in those 

 portions of the germ cells which rei)resent and will develop into the 

 corresponding organs of the future offspring? 



Previous fertilization. — Consider next the influence exerted upon 

 the fennile germ cell by the mere proximity of the male germ cell, as 

 exhibited in the transmission of the characteristics of one sire to the 

 offspring of a succeeding sire, observed in animals, including the 

 human species, also in plants. The best example is the oft-iputted 

 case of Lord Morton's mare, which reproduced in the foal of a i)urc 

 Arab sire the zebra markings of a previous quagga sire. 



Some physiologists t have attempted to account for these remark- 

 able indirect results from the previous fertilization or impregnation, 

 by the imagination of the mother having been strongly affected, or 

 from interchange between the freely inter-communicating circulation 

 of tiie embryo and mother, but the analogy from the action in plants 

 (in which there is no gestation but early detachment and development 

 of tlie fertilized cells) strongly supports the belief that the proximity 

 of male germ cells acts directly upon the female cells in the ovary. 

 All that we can deduce from these facts is that in sonn' manner the 

 normal characteristics and tendencies of the ova are modified by the 

 foreign male germ cells without either contact or fertilization. 



Maternal inqjression. — The influence of maternal impressions in the 



* Comptes-EendHS, March 13, 1882. These experiments have been contirmed by 

 Obersteiner. 



t See the cases cited by Ribot, and Darwin: Animals and I'lants Under DoimsHca- 

 iion, vol. I, p. 437.' 



