338 M. Flourens on the Action of the Spinal Marrow 



on the contrary, makes its appearance with a thick covering of 

 down, which falls off only as the feathers take its place. It is 

 still clothed as if intended to live in the country whence its pa- 

 rents have been but lately brought. 



The facts which I have above related were observed without 

 the preconceived idea of attaching them to any theory ; but on 

 examining them, one is naturally led, I think, to the following 

 inferences : — 



1*^, That, when certain animals are transported to a new cli- 

 mate, it is not the individuals only, but the races, that require 

 to be naturalized. 



2dli/, That when this naturalization takes place, there are 

 commonly produced in these races certain durable changes, 

 which bring their organization to a state of accordance with the 

 climates in which they are destined to live. 



Sdli/, That the habits of independence soon make the domes- 

 tic species resume the characters of the wild species from which 

 they have sprung. 



On the Action of the Spinal Marrow in Respiration. 

 By M. Floubens. 



JlivKRY body knows the opinion of the celebrated Legallois, 

 who was led by a series of experiments, then entirely new, to 

 place the seat of the principle of the motions of the heart in the 

 spinal marrow. 



M. Flourens shewed, in 1893, \st, Tliat the circulation, 

 which, in adult animals, is instantly stopped by the destruction 

 of the spinal marrow, on the other hand, survives its destruc- 

 tion a certain time in new-born animals : 9xilij, That, even 

 in adult animals (and this had already been determined by 

 Dr Wilson Philipp) the circulation survives the destruction of 

 the spinal marrow, provided the respiration be kept up by in- 

 sufflation. Thus, in the young animal, in which respiration is 

 less necessary to the circulation, the spinal marrow is also less 

 necessary. It is therefore especially because it is subservient to 

 respiration, that the spinal marrow is subservient to circulation. 



Whence it follows, that, if there were an animal in which the 



