BULLETIN OF THE BUSSEY INSTITUTION. 331 
on the berberry, in another on grain.. Perhaps the potato rot, after 
living for a certain length of time on the potato, and bearing asexual 
spores, passes in some way to an entirely different plant, and there 
bears its odspores. But to what plant does it change? We cannot 
tell, with the least degree of certainty. ‘There is a suspicion that it 
may be to clover or grain, wheat or oats, for example, from the general 
belief that the rot is very likely to appear when potatoes follow either 
of those crops. Lesides, the mycelium of a fungus supposed to have 
some connection with the potato-rot fungus has been found in clover 
‘and straw. Should this really prove to be the case, we shall have 
gained a valuable piece of information, since in no case should pota- 
toes be planted near or be allowed to alternate with either clover or 
grain, for fear of propagating the rot. Unfortunately, about this point 
theories are abundant and facts as yet scanty. There is by no means 
a unanimity of opinion as to whether potatoes are very likely to rot 
after clover, wheat, or oats. Of the fungus found on clover and on 
straw, we know nothing about the fruit of either kind, and, unless there 
is something more peculiar about the mycelium than we have been 
given to understand, it would be visionary to trace any particular con- 
nection with the potato-rot fungus. Botanists are, however, at work 
on the subject, and we may expect at any moment valuable discoveries 
in this direction. Professor De Bary, of Strasbourg, — whose memoir 
of the Peronospore, published in the “ Annales des Sciences Naturelles,” 
vol. xx. 1863, is the most exhaustive account of that group yet pub- 
lished, —is still at work, and from him we may receive a solution of the 
botanical difficulties. In the mean while, the American farmer can con- 
tribute something to the general stock of knowledge by noting the 
apparent effect which a different succession of crops has upon the prev- 
alence of the rot. In the Journal of the Royal Agricultural Society 
of England, vol. x. part 2, for 1874, are given the results obtained 
from answers to twenty-five questions, addressed to one hundred pota- 
to cultivators in different parts of England. From these answers, it 
would seem that there is a tendency for the rot to prove particularly bad 
when potatoes follow clover. Interesting facts on this point might be 
observed by our own cultivators to supplement those recorded in Eng- 
land, and we would propose the following questions for the considera- 
tion of farmers in connection with the rot: — 
