38 FOOT-NOTES TO EVOLUTION. 



All of these questions, and thousands more which will 

 suggest themselves at once to every student of embry- 

 ology, are problems which receive no adequate explana- 

 tion on the supposition of special creations. With the 

 theory of evolution as a basis, the answers are easy. 

 They are inheritances from ancestral conditions. In 

 the terms of evolution they remain because the history 

 of the individual is a more or less detailed recapitula- 

 tion of the history of the race. 



" The truth of this assumption is easily tested. The 

 conclusions of embryology must be in full accord with 

 those of geology, or one or the other must be wrong. 

 In the rocks we have an indisputable record of the suc- 

 cession of the forms of life, and the conclusions of em- 

 bryology must point to a similar succession. 



"While neither our limits nor the character of the 

 present article will allow anything like a discussion of 

 the embryological evidence in support of evolution, a 

 few examples will serve to indicate its character. 



" In the development of all eggs the earlier stages 



are essentially alike, or easily reducible to a common 



type. It is only in the later stages that 



imi an y o ^^^ variations occur that are to convert 



early stages in ■ ^ c u ^u ■ . 



embryonic life. o"^ egg mto a fish, another mto a 

 chicken. There are, it is true, minor 

 differences from the start, but these are largely to be 

 explained on mechanical grounds. An egg differs from 

 the other cells in the tissues of the parent chiefly in its 

 capacity to reproduce the species. It divides again and 

 again, and the resulting cells build anew the parent 

 form, but in the character of this division or * segmenta- 

 tion ' many variations are recognised. In some the 

 eggs are small and composed entirely of protoplasm, 

 and here the segmentation is regular, but other eggs are 

 larger, and this increase in size is due to the addition of 



