182 ANIMALS AND PLANTS. 



organism passes in the course of its life, are concerned, 

 the resemblance between Chlamydomonas and Hetero- 

 mita is of the closest description. And on the face of 

 the matter there is no ground for refusing to admit that 

 Heteromita may be related to Chlamydomonas^ as the 

 colourless fungus is to the green alga. Volvox may be 

 compared to a hollow sphere, the wall of which is made 

 up of coherent Chlamydomonads ; and which progresses 

 with a rotating motion effected by the paddling of the 

 multitudinous pairs of cilia which project from its sur- 

 face. Each Volvox-mon&d, moreover, possesses a red 

 pigment spot, like the simplest form of eye known 

 among animals. The methods of fissive multiplication 

 and of conjugation observed in the monads of this loco- 

 motive 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 sat- 

 isfactory, 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 nutriment, and which, 

 therefore, have a virtual, if not an actual, mouth and 

 digestive cavity, and thus come under Cuviers defini- 

 tion of an animal. Numerous forms of such animals 



