CULTUKE OF FARM CROPS. 



are met with, which are the causes of the most com- 

 mon of the diseases which infest the graminaceous plants. 

 These minute plants assume different forms ; sometimes, as 

 in the case of the fungus which we know by the name of 

 mould being made up of a series of minute sacs or cells 

 strung together by a bead-like process as in fig. 4, each of 

 which may be separated from the other, and yet as is sup- 

 posed still remain reproductive. Other fungi assume still 

 more complicated, and in many cases very beautiful, forms, 

 as in fig. 5, where the "sporules" or "spores" are seen ter- 



urinating the tips or extremities of the thread-like processes. 

 If, then, the plants themselves are so minute as a whole, 

 as we have already stated many of them are, some faint 

 notion may be obtained of the extreme minuteness of the 

 sporules by which they are propagated or multiplied. 

 Professor Henslow mentions that Fries one of the great- 

 est authorities in this branch of natural history calcu- 

 lated that a particular fungus might contain ten million of 

 sporules, while M. Bauer measured the spores of the species 

 of fungus (uredo foetida) known as "bunt " or " smut balls," 

 at 1 ^\ ) (j of an inch in diameter; so that a single grain of 

 wheat measuring only the thousandth part of a cubic inch 

 would contain 4,000,000 of sporules; while, then, it is 

 hardly possible to conjecture how many sporules each 

 spore* contains, since they are scarcely distinguishable 



* Professor Henslow (in his paper in the Journal of the Royal 

 Agricultural Society) gives the following note, which may be useful 



