1915] The Ottawa Naturalist. 91 



microscopic points capped with enamel, which indicate its an- 

 cestral connections. They are absorbed before the bird is many- 

 days old. In the unborn parrot is the vanishing point of a 

 "missing link " with its primeval progenitors. 



With the disappearance of the primeval swamp has also 

 disappeared the five-toed ancestor of the horse. Transferred 

 to the plains, he now races free upon a single digit, developed 

 into a hardened hoof, leaving the vanishing remains of other 

 digits within his pastern to mark the transition of slow develop- 

 ment, through aeons of time, from one form of life to another. 

 These are instances of a plastic power within the living organism 

 which enables it to fit itself in, and adapt itself to, the exigencies 

 of its environments. The very urgencies of subsistence, and 

 the necessities of survival at Nature's table, demand this con- 

 stitutional tendency to impermanence of form or function. 



Variability of Nature and Life. 



For in all her physical aspects, Nature is herself changeable" 

 and inconstant. The rigors of her chequered and ever-change- 

 able conditions have aided in eliciting and fixing the quality 

 of mutability in her life forms. There is thus an element of 

 mutability and reciprocation between the internal organism and 

 its external surroundings. And the instability of the organism- 

 is a natural and a necessary part of the dual state of its existence .■ 

 As Herbert Spencer has sententiously remarked in defining life 

 itself, it is "a continuous adjustment of internal relations with 

 external relations." Such, in brief, is the doctrine of variation, 

 which is the starting point of Darwin's theory of the origin of 

 species and the evolution of life. 



Darwin at once seized hold of the enormous range of varia- 

 tion seen in domestic species, and its power of diversity and ex- 

 tension under the hand of the expert breeder and cultivator. 

 And in utilising its multifarious phenomena in support of his 

 thesis, he personally experimented with both animal and vege- 

 table species. Here he showed that the key of man's power 

 over species lies in the accumulation of his selections of varying 

 and variable points of structure and character. Nature pro- 

 vides variations, and their succession in heredity. Man adds 

 them up in directions useful to him. In this way he has built 

 up great and serviceable breeds. He can not merely modify 

 the character of his types, but he can change them altogether. 

 It does not require a great eflfort of the imagination to 

 determine the motives of man in his selection and improvements 

 of breeds to serve his ends. It is known that sheep skins were 

 used for tents, as well as for clothing and foot-wear, from the 



