78 MEANING OF ORDERS. 
Animal Kingdom into the Apathetic, Sensitive, 
and Intelligent animals. The Apathetic were 
those devoid of all sensitiveness except when 
aroused by the influence of some external agent. 
Under this head he placed five classes, includ- 
ing the Infusoria, Polyps, Star-Fishes, Sea-Ur- 
chins, Tunicata, and Worms,—thus bringing 
together indiscriminately Radiates, Mollusks, and 
Articulates. Under the head of Sensitive he 
had also a heterogeneous assemblage, including 
Winged Insects, Spiders, Crustacea, Annelids, 
and Barnacles, all of which are Articulates, and 
with these he placed in two classes the Mollusks, 
Conchifera, Gasteropoda, and Cephalopoda. Un- 
der the head of Intelligent he brought together a 
natural division, for he here united all the Ver- 
tebrates. 
He succeeded in this way in making out a 
series which seemed plausible enough, but when 
we examine it, we find at once that it is perfectly 
arbitrary; for he has brought together animals 
built on entirely different structural plans, when 
he could find characters among them that seemed 
to justify his favorite idea of a gradation of qual- 
ities. Blainville attempted to establish the same 
idea in another way. He founded his series on 
gradations of form, placing together in one divis- 
ion all animals that he considered vague and in- 
definite in form, and in another all those that he 
