184 ANIMALS AND PLANTS vi 



whom I have borrowed this history have en- 

 deavoured to ascertain whether their monads take 

 solid nutriment or not ; so that though they help 

 us very much to fill up the blanks in the history 

 of my Heteromita, their observations throw no 

 light on the problem we are trying to solve Is it 

 an animal or is it a plant ? 



Undoubtedly it is possible to bring forward 

 very strong arguments in favour of regarding 

 Heteromita as a plant. 



For example, there is a Fungus, an obscure and 

 almost microscopic mould, termed Peronospora 

 infestans. Like many other Fungi, the Pcrono- 

 sporce are parasitic upon other plants; and this 

 particular Peronospora happens to have attained 

 much notoriety and political importance, in a way 

 not without a parallel in the career of notorious 

 politicians, namely, by reason of the frightful 

 mischief it has done to mankind. For it is this 

 Fungus which is the cause of the potato disease ; 

 and, therefore, Peronospora infestans (doubtless of 

 exclusively Saxon origin, though not accurately 

 known to be so) brought about the Irish famine. 

 The plants afflicted with the malady are found to 

 be infested by a mould, consisting of fine tubular 

 filaments, termed hyphm, which burrow through 

 the substance of. the potato plant, and appropriate 

 to themselves the substance of their host ; while, 

 at the same time, directly or indirectly, they set 

 up chemical changes by which even its woody 



