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 waving 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 investigatedby 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' 7 of plum and cherry 

 trees is an 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 fungus 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 



