180 ANIMALS AND PLANTS. 



tinctive character of vegetable life ; or, at any rate, that 

 there is no proof that it does not get its protein matter 

 ready made from the potato plant. 



Let us, therefore, take a case which is not open to 

 these objections. 



There are some small plants known to botanists as 

 members of the genus Coleochcete, which, without being 

 truly parasitic, grow upon certain water-weeds, as lichens 

 grow upon trees. The little plant has the form of an 

 elegant green star, the branching arms of which are 

 divided into cells. Its greenness is due to its chlorophyll, 

 and it undoubtedly has the manufacturing power in full 

 degree, decomposing carbonic acid and setting oxygen 

 free, under the influence of sunlight. But the proto- 

 plasmic contents of some of the cells of which the plant 

 is made up occasionally divide, by a method similar to 

 that which effects the division of the contents of the 

 Peronospora spore ; and the severed portions are then 

 set free as active monad-like zoospores. Each is oval 

 and is provided at one extremity with two long active 

 cilia. Propelled by these, it swims about for a longer or 

 shorter time, but at length comes to a state of rest and 

 gradually grows into a ColeochoBte. Moreover, as in the 

 Peronospora, conjugation may take place and result in 

 an oospore ; the contents of which divide and are set 

 free as monadiform germs. 



If the whole history of the zoospores of Peronospora 

 and of Coleochcete were unknown, they would undoubt- 

 edly be classed among " Monads " with the same right 



