546 Causes and Course of Organic Evolution 



Lauder Lindsay, Romanes, and others in recent years have all 

 emphasized the striking mental advance shown by members 

 of the above groups over their fellows, or even over related 

 groups that have shown little advance or even retrogression. 



But our present aim is to demonstrate further the intimate 

 bond existing between advancing nerve complexity and the 

 exhibition of biotic, cognitic, and cogitic energies in connection 

 therewith. Here it will be observed that the convenient and 

 also morphologically correct hard and fast division into inverte- 

 l^rates and vertebrates, or into the more important minor 

 groups of these, is set aside, for, while alike convenient and 

 natural as an aid and index to general morphological and taxo- 

 nomic distinctions, it entirely breaks down when we view 

 animals from the biological or, to express it more exactly, the 

 most energized and nerve-responsive standpoint. 



The principles now to be dwelt on and expanded may first 

 in part be illustrated by the annexed diagram in which the 

 solid black lines set forth the taxonomic as well as ancestral 

 dignity of the groups, while the broken lines indicate the degree 

 of cognitic aiid of cogitic advance to which the highest repre- 

 sentatives of the groups have attained (Fig. 27). 



In reference to this diagram it may at first glance seem strange 

 and even false to regard ants as greatly higher than fishes, 

 batrachians, or even reptiles and many birds, even though 

 Lubbock half a century since wrote: "If we judge animals by 

 their intelligence as evinced in their actions, it is not the gorilla 

 and the chimpanzee, but the bee, and above all the ant, which 

 approach nearest to man" {177: 65.) But, if the evidences 

 advanced below prove anything, they clearly demonstrate that 

 some genera or groups, owing to certain combined biological 

 factors, have run far ahead, in certain evolutionary character- 

 istics, of the average members of their group. It is of prime 

 importance then to learn what these factors have been, and how 

 they have operated. 



In the embryological development of every animal from the 

 lower nemerteans upward, the first fundamental change noted 

 in the multicellular embryo is the formation from the epi- 



