State Museum oF NATURAL HISTORY. 25 
them were detected. ‘The leaves of many plants often became dis- 
colored in spots or would wither and die in an unaccountable manner ; 
the branches of plum trees and cherry trees bore black and unsightly 
excrescences which at length caused them to die ; potato vines were 
suddenly affected with blackish spots and premature death, and the 
tubers themselves rotted mysteriously, either in the ground or out of 
it ; fields of waying grain were struck with “‘ rust” that was not due 
to any oxidation ; stems and leaves of grass and grain were ‘‘ branded ” 
in blackish lines, yet not by the use of fire; Indian corn often pro- 
duced turgid, smutty excrescences on the ears that should have been 
well filled with golden grain ; the products of the fruit trees and the 
orchards would speedily decay without any apparent or satisfactorily 
explainable cause; the sweetened juice of grapes and other fruits 
would quickly ferment, effervesce and indicate chemical activity with- 
out the introduction of any chemical reagents ; preserved fruits would 
often turn sour or musty ; even sweet milk would not retain its sweet- 
ness long ; wood thoroughly dried and kept so, or if kept constantly 
submerged, was found to be almost imperishable, but in intermediate, 
circumstances it would speedily decay. These and many other phe- 
nomena were noticed, and their causes were sometimes made the sub- 
ject of speculative theories, but the real agencies that produced them 
were not and could not well be fully understood till investigated by the 
aid of the microscope. When by this means our powers of vision have 
been sufficiently increased, we find that the dead spots on leaves usually 
bear crops of minute fungi, that the ‘‘ black knot” of plum and cherry 
trees is au enlargement of the branch covered by a fungus whose threads 
have caused the mischief, that the spots on the potato leaves and 
the consequent rotting of the tubers are the work of a minute parasiti- 
cal fungus, that the “rusts” and “brands” of the grain fields, the 
smut of corn, the decay of fruits, the fermentation of juices, the sour- 
ing of milk and other substances and the rotting of wood are all due 
to the presence of fungi of one kind or another. And now that the 
microscope has disclosed this previously almost invisible world of vege- 
tation and we have entered upon its investigation, we can only won- 
der at its extent and importance. We find these minute organisms 
endowed with certain definite forms and certain fixed structural char- 
acters by means of which they can be systematically classified and 
specifically designated just as readily as the ordinary plants we see 
about us. We find in many instances that they have peculiar habits 
and habitats to which they are addicted, so that a knowledge of the 
habitat and behavior of the fungtis is many times sufficient to indi- 
cate pretty accurately the systematic character of the parasite. 
We have already learned that nearly all flowering plants, whether 
cultivated or wild, have one or more parasitic fungoid foes to whose 
attacks they are sometimes subject. Some plants have several of these 
enemies that attack them in one part or another, at one time or another, 
while some more fortunate are rarely affected and then only under cir- 
cumstances peculiarly favorable to the parasite. Besides the fungi that 
attack only living plants, there are multitudes of species that are often 
less particular concerning their habitat and that revel promiscuously 
upon the tissues of dead plants. Nor can we stop here, for living animal 
[Assem. Doc. No. 127.] 4 
