134 EVOLUTION OF TO-DAY. 



Let us not lose sight of the problem we are trying 

 to solve, which is the reason for the contradictions 

 found in the embryological histories of allied animals. 

 We have seen some of the causes which have led to 

 the modification of the embryological record, and it 

 may well happen that two allied animals may be 

 modified in different degrees. And we may find 

 some cases where there is still retained what is 

 known as the primitive history, i. e., a development 

 which so far as we can judge repeats quite exactly 

 the past history. Of course when it is recognized 

 that the embryological record can be modified, there 

 will be difficulty in deciding just what the primitive 

 history is. If it is admitted that the record can be 

 modified in some respects, what right can there be 

 in saying that any given history is unmodified ? 

 Naturalists of note have claimed that where the 

 falsification of the record is once admitted, the whole 

 data for work is gone ; the embryologist has used 

 up his foundation in trying to build his structure. 

 That there is a difficulty here no one will deny ; 

 but it is not an insurmountable one. Every new 

 fact of embryology aids in the solution of the prob- 

 lem, and by taking all of the facts together some 

 general rules can be deduced which aid in solving 

 the difficulties here presented. From what has 

 been already said, it will be evident that in embryos 

 which have no food supplied them in the egg, we 

 may expect a more primitive history than in those 

 cases where such food is abundant. Free living 

 embryos we might expect would be less modified 

 than those passing their development in the body 



