VII.] ANIMALS AND PLANTS. 169 



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 in- 

 festans. Like many other Fungi, the Peronosporce 

 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, consist- 

 ing of fine tubular filaments, termed hyphce, 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 framework becomes blackened, sodden, and 

 withered. 



In structure, however, the Peronospora is as much 

 a mould as the common Penicillium; and just as the 

 Penicillium multiplies by the breaking up of its hyphae 

 into separate rounded bodies, the spores; so, in the 



