THE PATH OF EVOLUTION 



pared, as demanded, not from a storehouse provided 

 in advance, as in the egg. With those born living 

 the conversion of food into tissue and the oxidation 

 of the carbohydrates and the nitrogenous albuminoids 

 in the parent, elevate a portion into the higher plane 

 of organization requisite for the existing life and 

 for the new one forming; the phenomena of the 

 growth of sensation, of consciousness, and of will, 

 being equally as impossible to comprehend in the 

 vivipara as it is with the ovipara. 



The new-formed embryo, being the inheritor of the 

 protoplasmic cell structure from each of its parents, 

 inherits likewise their individual idiosyncrasies. As 

 the adults can only have fertile offspring when they 

 are closely allied in species and conformation, their 

 young will usually represent very nearly the average 

 of the breed from whence they have sprung. The 

 tendency to resemble the inherited traits of one line 

 of parentage more than that of another is dependent 

 upon the conditions of relative adaptation of either 

 parent structure to the needs of its existence, and the 

 consequent development in its offspring of that form 

 of structure that is best fitted for its life, rather than 

 that of the other form. Thus are introduced varia- 

 tions in some of their descendants that give rise in 

 time to so great changes that new species are formed. 

 The details, causes and conditions thereof constitute 



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