1911.] the Transmission of Acquired Characters. 



577 



of Brown-Sequard that there were always malformations of the toes in 

 these cases supports this view. 



20. From direct observation, and from a consideration of the high rate 

 of mortality, it may be supposed that the young of guinea-pigs which shew 

 the phenomenon are less healthy than are normal guinea-pigs. There 

 may then be a less efficient grooming of the skin, and, in consequence, the 

 excitability of the scratch-reflex will be raised, as in other animals. This 

 makes of little value evidence that the phenomenon appears sooner after 

 division of the nerve in the young of guinea-pigs which already have the 

 phenomenon than in the young of normal guinea-pigs, even if that evidence 

 be definitely established. 



21. We may conclude by saying : — 



An examination of the " Brown-Sequard phenomenon " in guinea-pigs — 

 usually considered to be a classical instance of the alleged transmission 

 of an acquired character — throws much doubt upon its value in this 

 controversy. 



The phenomenon is not an acquired peculiarity produced de novo on 

 division of a great sciatic nerve. It is due to the raised excitability of a 

 mechanism — that of the scratch-reflex — already present ; and this raised 

 excitability is probably due to the removal of an inhibiting influence by 

 section of the nerve. 



The phenomenon, therefore, cannot be considered as transmissible as 

 an acquirement per sc. If anything is transmitted as an acquired character 

 it must be the state of raised excitability of the scratch-reflex. 



The presence of the phenomenon in the offspring observed by Brown- 

 Sequard may be admitted, but this may be explained otherwise than by 

 assuming a transmission of acquired characteristics. 



That the alternative explanation — the presence in the offspring is due 

 to a production of the state by injury to the toes and feet inflicted by the 

 parent — is true is rendered possible, and indeed highly probable, by certain 

 parallel evidence submitted in this paper. 



REFERENCES. 



1. Brown-Sequard, C. E., ' Compt. Rend. Soc. Biol.,' 1850, p. 105. 



2. „ „ ' Gaz. Med. de Paris,' 1850, p. 651. 



3. „ „ ' Compt. Rend. Soc. Biol.,' 1850, p. 134. 



4. „ „ ibid., 1850, p. 169. 



5. „ „ ' Gaz. Med. de Paris,' 1850, p. 895. 



6. „ „ 'Journ. de la Physiol.,' 1858, p. 241. 



7. „ „ ibid., 1860, p. 167. 



8. „ „ ' Roy. Soc. Proc.,' 1860, vol. 10, p. 297. 



