ANIMALS AND PLANTS. 181 



as Heteromita why then may not Ileteromita, be a 

 plant, even though the cycle of forms through which it 

 passes shows no terms quite so complex as those which 

 occur in Peronospora and Coleochoete? And, in fact, 

 there are some green organisms, in every respect charac- 

 teristically plants, such as Chlamydomonas, and the com- 

 mon Vblvox, or so-called "Globe animalcule," which 

 run through a cycle of forms of just the same simple 

 character as those of Heteromita. 



The name of Chlamydomonas is applied to certain 

 microscopic green bodies, each of which consists of a 

 protoplasmic central substance invested by a structureless 

 sac. The latter contains cellulose, as in ordinary plants ; 

 and the chlorophyll which gives the green colour enables 

 the Chlamydomonas to decompose carbonic acid and fix 

 carbon as they do. Two long cilia protrude through the 

 cell - wall, and effect the rapid locomotion of this 

 " monad," which, in all respects except its mobility, is 

 characteristically a plant. Under ordinary circumstances, 

 the Chlamydomonas multiplies by simple fission, each 

 splitting into two or into four parts, which separate and 

 become independent organisms. Sometimes, however, 

 the Chlamydomonas divides into eight parts, each of 

 which is provided with four instead of two cilia. These 

 k < zoospores " conjugate in pairs, and give rise to quies- 

 cent bodies, which multiply by division, and eventually 

 pass into the active state. 



Thus, so far as outward form and the general char- 

 acter of the cycle of modifications, through which the 



