42 



melon fuugus lived in a dried-out condition in one of my agar tube 

 cultures tbrec and one-half years; in another it was alive at the end 

 of ten months and twenty-three days; in a third trial it was found 

 alive in 7 out of 8 test-tube cultures which had been in a warm, dry 

 place in a dried-out condition for nearly two years. These last tubes 

 were inoculated at various dates between July 26 and October 8, 1894, 

 and the test was made January 19, 1897. The ascospores of the 

 cowpea fungus remained alive iu a dry condition 16 mouths.^ 



SYMPTOMS PRODUCED, ETC. 



The gross symptoms in the watermelon are sufficiently shown on the 

 accompanying plates (Pis. VII, VIII, X). They are those of a plant 



of which vshort sprouts frequently push out. This disease was first studied hy the 

 writer in 1895. It a+tacks the plant in the same way as the melon fungus — i. e., from 

 the soil — and destroys it by plugging the water ducts. It first produces iu the ves- 

 sels of the living plant great numbers of microconidia (8 to 13 by 2 to 4 //), and then 

 macroconidia on the surface, in the same way as the melon fungus. In July, 1895, a 

 quantity of soil was obtained from one of these badly infested fields (near Albany, 

 N. Y. ) and was stored away in a dry basement for three and one-half years. It was then 

 removed from its original packings, put iuto a clean pine box made from freshly 

 planed lumber, planted with three varieties of cabbage, placed in an upper window of 

 an unoccupied laboratory room, and watered with distilled water. Some of the plants 

 were attacked by Pythium and others by this Fusarium, which was found fruiting in 

 the vessels. The checks did not contract the disease. The conditions under which 

 the experiment was made point unmistakably to the soil as the source of the infec- 

 tion in case of these plants. This experiment, in connection with those which have 

 been made on the watermelon, renders it probable that all parasitic soil Fusaria are 

 alike in being very resistant to tlrought and other conditions unfavorable to vegeta- 

 tive life. 



Embolisms of the vascular system due to fungi of the form-genus Fusarium are 

 now known to the writer in plants of many different families. (See partial list on 

 p. 43.) Most if not all of these fungi enter the plant from the earth. The fungi 

 occurs so regularly in connection with these diseases that we are warranted in 

 assuming them to be parasitic, although as yet in most cases no infection experi- 

 ments have been instituted or brought to a successful conclusion. Judging from 

 the results obtained with the watermelon and cabbage, it appears extremely prob- 

 able that iu the Cephalosporium and Fusarium stages of a variety of Nectriaceous 

 fungi we have to deal with a large group of destructive soil parasites the very 

 existence of which, in the earth, as active jjarasites, was not suspected until very 

 recently — i. e., until the announcement of my results in 1894. (Am. Asso. Adv. Sci.) 



' Some additional tests were begun September 28, 1899, as this bulletin was passing 

 through the press. The watermelon fungus was found to be dead iu each one of the 

 10 bread cultures already mentioned (p. 16) and in a few other cultures of the same 

 age (hominy, cowpeas), but was still alive in numerous test-tube cultures of horse 

 dung. These were made October 27, 1894 (from internal and external conidia), and 

 have been dried out for at least four and one-half years. Twenty-two tubes were 

 tested, and the fungus was found alive in each one. 



Four test-tube cultures of the cotton fungus (from internal conidia) were also 

 tried at the same time, and the fungus was found to be alive in each one. These 4 

 cultures were 5 years old. They were made on sterilized stems of the watermelon, 

 October 3, 1894, and have been dried out and in a dry laboratory for at least four and 

 one-half years. 



The cowpea fungus (ascospore strain) was dead iu each one of the 12 banana 

 cultures made December 6, 1895. 



