REPORT OF THE MYCOLOGICAL SECTION. 



Sir: Appointed by you, upon the 1st of last July, to take charge of 

 the section of the Botanical Division, devoted to the "investigation 

 of tlie diseases of fruits and fruit trees, grains and other useful plants, 

 caused by fungi," I have the honor to make the following report: 



It will be seen from the very nature of the work of this section 

 that it is too early to expect the attainment of any definite results 

 from original investigations, and whatever subjects are now.discussed 

 can only be looked upon as preliminary to more complete and ex- 

 haustive studies. 



The fungi which infest our cultivated plants, and not infrequently 

 cause their total destruction, vie with the insect tribes in numbers 

 as well as in the extent of the losses they occasion, and the transfor- 

 mations they undergo in their development are equally complex and 

 often even more difficult to follow. They are, for the most part, so 

 small, and the metamorphoses they undergo so obscure, as to call for 

 the greatest amount of patience and the closest study in order to 

 obtain any satisfactory knowledge of their natural history, and in 

 spite of all our efforts there will frequently remain many points 

 which must be left to conjecture. 



That these fungi, which make themselves manifest in the plant 

 diseases familiarly known as "rust," "smut," "mildew," "blight," 

 &c., are true vegetable parasites; that they are governed by the same 

 laws which control all living organisms; and that they are propa- 

 gated by specially developed reproductive bodies called spores, are 

 fundamental truths to be kept constantly in mind in studying this 

 subject. There is no such thing as spontaneous generation among 

 these parasites, and whenever a fungus appears it is as certain that 

 it was preceded by a spore as that the oak came from an acorn, 

 and, further, that the germination of the acorn and spore was only 

 effected by surroundings and conditions favorable to its accomplish- 

 ment. We have a pretty fair knowledge of what these conditions 

 are in the one case, but simply because those in the other are not so 

 well understood we must not deny their existence. 



In order to make an intelligent use of remedies for checking or 

 preventing the ravages occasioned by injurious fungi, which is the 

 primary and ultimate object of the work of this section, it is mani- 

 festly essential to gain a complete knowledge of their nature and 

 habits. To accomplish this will require much time and research, 

 but in no other way can we hope to attain results of positive value. 

 Those species which grow within the tissues of the plants they infest 

 demand a different treatment from those Avhich live wholly upon the 

 surface. Species which live only for a time upon some useful plant, 

 passing the remainder of their existence upon some worthless weed 

 or son\e plant in decay, can be managed differently from those that 

 infest only a single host. A complete knowledge of the life history 

 of these parasites cannot fail to bring to light some weak point iii 

 their development which may be taken advantage of in seeking their 

 destruction. 



(95) 



