1 62 EVOLUTION" OF TO-DAY. 



with each other. Adult anatomy seems to teach 

 that although the various types are nearer together 

 at the bottom than they are at the top, yet there is 

 no evidence to show that they are united. And the 

 same result arises from the study of fossils; for 

 while undoubtedly the record of paleontology does 

 prove convergence of lines and the union of many 

 smaller groups, the great types are as distinct from 

 each other at the earliest times of which we have 

 any record as they are now. While, therefore, such 

 studies indicate the common union of the animal 

 kingdom at a starting-point, they leave it only a 

 matter of inference. 



The first assistance which embryology gives 

 toward a solution of the animal kingdom, is in 

 completing this chain of evidence. A long and 

 careful study of development has brought to light 

 the marvellous fact that the embryology of the in- 

 dividual is a brief repetition of the past history of 

 the race, a law which, subject to certain limitations 

 already discussed, is found to be in complete har- 

 mony with the facts as now known. The existence 

 of this law is the argument of real significance which 

 embryology has to offer, for it is a law readily follow- 

 ing from the descent theory, but unintelligible other- 

 wise. Using this law to interpret the past, it is 

 found that all animals start together at a com- 

 mon point, all begin life to-day as a unicellular 

 ovum. Not only this, but for some distance they 

 can be followed over the same road, until a stage is 

 reached which is called the gastrula. Now if the 

 parallel means any thing, this indicates that all ani- 



