148 PLANT DISEASE 



weeds thrive, it is easy to understand how a 

 dressing of iron to the soil that would be very 

 beneficial to our common farm crops like the 

 cereals, clovers, turnips, etc., would be very 

 injurious to many of these weeds. 



This is certainly the case with two forms of 

 plant life, the fungi and cuscuta. 



Considering these plants as parasites of 

 higher forms of plant life, the evidence, though 

 not conclusive, goes to show that they live 

 upon the higher forms only when these latter 

 are deficient in chlorophyll matters, by which 

 I mean not only iron and nitrogen, but the 

 proteids generally. We know of fungi ranging 

 from the smallest bacteria up to mushrooms, 

 the marked feature of their existence being an 

 entire absence of chlorophyll. We also have 

 several cuscuta which, I take it, are a higher 

 form of plant life than the fungi, containing 

 no chlorophyll. We have creeping fungi, as 

 well as certain low forms of animal life, such 

 as slugs, which do considerable damage. 

 Slugs, indeed, living as they do like the fungi 

 mainly upon decaying vegetable matter, are 

 not unlike creeping fungi, and I believe it can 

 be shown that they are chemically of a similar 



