VII. ] ANIMALS AND PLANTS. 175 



monad, moreover, possesses a red pigment spot, like 

 the simplest form of eye known among animals. 

 The methods of fissive multiplication and of con- 

 jugation observed in the monads of this locomotive 

 globe are essentially similar to those 'observed in 

 Chlamydomonas ; and, though a hard battle has been 

 fought over it, Volvox is now finally surrendered to 

 the Botanists. 



Thus there is really no reason why Heteromita 

 may not be a plant ; and this conclusion would be 

 very satisfactory, if it were not equally easy to show 

 that there is really no reason why it should not be an 

 animal. For there are numerous organisms presenting 

 the closest resemblance to Heteromita, and, like it, 

 grouped under the general name of " Monads/' which, 

 nevertheless, can be observed to take in solid nutri- 

 ment, and which, therefore, have a virtual, if not an 

 actual, mouth and digestive cavity, and thus come 

 under Cuvier's definition of an animal. Numerous 

 forms of such animals have been described by Ehren- 

 berg, Dujardin, H. James Clark, and other writers on 

 the Infusoria. Indeed, in another infusion of hay 

 in which my Heteromita lens occurred, there were 

 innumerable infusorial animalcules belonging to the 

 well-known species Colpoda cucullus. 1 



Full-sized specimens of this animalcule attain a 

 length of between ^^ or ^^ of an inch, so that it 

 may have ten times the length and a thousand times 

 the mass of a Heteromita. In shape, it is not alto- 



1 Excellently described by Stein, almost all of whose statements I 

 have verified. 



