IX 



THE HISTORY AND SCOPE OF ZOOLOGY 



345 



logie and the Schopfungsgeschichte. Haeckel himself, 

 with his pupil Miklucho-Maclay, had in the meantime 

 made studies on the growth from the egg of Sponges, 

 studies which resulted in the complete separation of 

 the unicellular or equicellular Protozoa from the 

 Sponges, hitherto confounded with them. It is this 

 introduction of the consideration of cell- structure and 

 cell-development which, subsequently to the estab- 

 lishment of Darwinism, has most profoundly modified 

 the views of systematists, and has led in conjunction 

 with the genealogical doctrine to the greatest activity 

 in research, an activity which culminated in the 

 work (1873-1882) of F. M. Balfour, and produced the 

 profoundest modifications in classification. 



Haeckel's earlier pedigree is worth comparing with 

 his second effort, as showing the beginning of the influ- 

 ence just noted. The second pedigree is as follows : 



Phyla. 



Protozoa. 

 Zoophyta. 



Classes. 

 f Archezoa. 

 < Gregarince. 

 ( Infusoria, 

 l Planceada. 

 \ Gastrceada. 

 Porifera. 



Vermes. 



I ACALEPH.E. 



AC(ELOMI. 



C(ELOMATI. 



< Hydromedusce. 

 { Ctenophora. 



Platyhelminthes. 



Nemathelminthes. 



Bryozoa. 



Tunicata. 



Rhynchocosla. 



Gephyrcea. 



Rotatoria. 



Annelida. 



