192 ANIMALS AND PLANTS vi 



small actively vibrating ciliary organs, which are 

 only longest at the small end. At the point 

 which answers to that from which the two cilia 

 arise in Heteromita, there is a conical depression, 

 the mouth ; and, in young specimens, a tapering 

 filament, which reminds one of the posterior cilium 

 of Heteromita, projects from this region. 



The body consists of a soft granular proto- 

 plasmic substance, the middle of which is occupied 

 by a large oval mass called the " nucleus " ; while, 

 at its hinder end, is a " contractile vacuole," con- 

 spicuous by its regular rhythmic appearances and 

 disappearances. Obviously, although the Colpoda 

 is not a monad, it differs from one only in subor- 

 dinate details. Moreover, under certain conditions, 

 it becomes quiescent, incloses itself in a delicate 

 case or cyst, and then divides into two, four, or 

 more portions, which are eventually set free and 

 swim about as active Colpodce. 



But this creature is an unmistakable animal, 

 and fall-sized Colpodce may be fed as easily as one 

 feeds chickens. It is only needful to diffuse very 

 finely ground carmine through the water in which 

 they live, and, in a very short time, the bodies of 

 the Colpodce are stuffed with the deeply-coloured 

 granules of the pigment. 



And if this were not sufficient evidence of the 

 animality of Colpoda, there comes the fact that it 

 is even more similar to another well-knowm 

 animalcule, Paramcecium, than it is to a monad, 



