300 Journal of Agricultural Research voi. xiii, no. s 



Sporophores arise singly on the lower surface of the leaf as branches of the mycelium, 

 hyalin to light brown, i- to s-septate, lo to 30 by 7 to 12 ju, the individual cells eventu- 

 ally becoming globose and easily breaking apart, bearing a single spore at the apex. 



The spores are nearly globose, dark brown, muriform, 25 to 50M in diameter, com- 

 posed of 5 to 20 cells each of which are 10 to 18 n in diameter, easily breaking av/ay 

 from the sporophores. They develop abimdantly on the lower surface of leaves and 

 on several of the ordinary culture media. 



Habitat: Leaves, rarely stems and petioles, of Cucumis sativus and Cucurbita pepo 

 (gourds and summer squash). The type specimen was collected from a cucumber 

 field, near Plymouth, Ind., on September 27, 1915. Specimens were also collected 

 from Lapaz and Lakeville, Ind., in September, 1915, and Bowling Green, Ohio, in 

 October, 191 5 (W. W. Gilbert); Hamlet and North Liberty, Ind., in September, 1916. 



The type specimen has been deposited in the herbarium of the United 

 States Department of Agriculture, Washington, D. C. Duplicates of 

 this type material have been deposited in the herbaria of the New York 

 Botanical Garden, New York, the Harvard Cryptogamic Laboratory, 

 Cambridge, Mass., and the Department of Botany, Purdue University 

 Agricultural Experiment Station, La Fayette, Ind. 



CULTURAL CHARACTERS OF THE FUNGUS 



The fungus has been grown on the following media: Corn-meal agar, 

 beef agar, Lima bean agar, oat agar, potato-glucose agar, potato plugs, 

 cucumber-stem agar, string-bean agar, and beef bouillon. On standard 

 beef agar and in bouillon a limited growth with slight spore production 

 occurs. On potato-glucose agar and string-bean agar abundant growth 

 with abundant spore production takes place. The growth on the other 

 media tried is intermediate between these two. 

 The growth on one series of string-bean-agar cultures will be given in 

 detail as a typical example. These transfers were made on November 9, 

 1 91 6, with spores from a 15-day-old culture. 



November 11, 1916. — Growth was visible around point of inoculation as light radi- 

 ating strands of mycelium . 



November 14, 1916. — Growth around point of inoculation was rather granular for 

 2^ to 3 mm. in diameter. Light radiating growth around this was 6 to 8 mm. in diam- 

 eter. Examination with a binocular microscope showed that the granular appearance 

 was due to the beginning of spore formation. A few drops of liquid were present on 

 mycelium in some tubes, owing to exudation. 



November 17, 1916. — Growth was 12 to 14 mm. in diameter. A thin layer of brown 

 spores 8 to 10 mm. in diameter, with granular-appearing mycelium, surrounded this. 

 Around portions of the margin there was a narrow light flocculent gro\\'th where spore 

 formation had not yet begun. 



November 22, 1916. — Growth was 16 to 20 mm. in diameter. The surface was almost 

 entirely covered with a heavy dark-brown or nearly black mass of spores. The spore 

 formation was less abundant at the edge, or in places was absent. A few white tufts 

 of mycelium i to 2 mm. in diameter had appeared over the spores. 



December i, 1916. — Heavy dark spore masses appeared in all the tubes, partly cov- 

 ered by a white fluffy growth of mycelium. 



