ACQUIRED CHARACTERS 31 



From 1869 to 1891 Brown-Sequard experimented on thou- 

 sands of guinea-pigs, developing methods by which a certain 

 form of epilepsy could be induced through injury to different 

 parts of the nervous system, such as the spinal cord or the 

 sciatic nerve. In some cases the young of animals thus 

 rendered epileptic were themselves similarly affected. Some 

 persons who have repeated Brown-Sequard's experiments 

 confirm his results, notably Romanes; others have failed to 

 confirm them. 



Weismann has suggested that some pathogenic organism 

 may have got into the wounds and, migrating into the central 

 nervous system, have caused the epilepsy, and this same or- 

 ganism may have infected the young. There is no evidence 

 that such was the case, however. 



Guinea-pigs are said to be strongly predisposed to epilepsy, 

 and so the results of Brown-Sequard's experiments may be 

 pure coincidences, or due to the transmission of a chemical 

 substance. In some cases reported by Brown-Sequard the 

 animals gnawed off one or more toes after the sciatic nerve 

 had been cut. Certain of their young are reported to have 

 done the same. This is almost certainly pure coincidence, 

 since the evidence as regards the inheritance of mutilations 

 is unmistakable. 



4. Acclimatization. It is well known that animals or plants 

 taken from one climate to another undergo changes of form. 

 The same plant divided into two parts and planted one part 

 upon an exposed mountain side, the other in a sheltered, 

 fertile valley, assumes forms very different in the two places. 

 The mountain form is short, compact and dwarfed; the val- 

 ley form is tall, spreading and luxuriant. It is assumed by 

 Lamarckians that these direct effects of the environment are 

 to some extent inherited, that if they are repeated through a 

 long series of generations they at last become habitual ^ so to 

 speak, and appear spontaneously even when the external 

 cause is lacking. In this way it is explained why mountain 

 species in general are dwarfed, and lowland species are tall 

 and luxuriant, even when the two are grown side by side 



