284 PROCEEDINGS OF THE AMERICAN ACADEMY. 



is as a rule scantily developed in older cultures only, but by using a 

 special nutrient composed of a decoction of bran, Spanish chestnuts,, 

 horse dung and rotten wood hardened with agar, an abundant pro- 

 duction of conidia was obtained after two months, the conidiophores 

 (Figures 35-36, Plate 12) rising well above the substratum at the mar- 

 gin of the culture, so that large quantities of spores were readily 

 obtained in an absolutely pure condition. Cultures of these yielded 

 about two per cent of germinations after twenty days. 



The development of these germinating conidia (Figures 3S-41, 

 Plate 12) was continuously followed in Van Tieghem cells until 

 bulbils were produced on the mycelium derived from them. 



The conidiophores (Figures 35-36, Plate 12) which are colorless at 

 first but become light grayish brown at maturity, are larger (3.5—1 /i 

 in diameter) than the other hyphae from which they arise, with quite 

 irregular walls producing numerous lateral conidia which rest either 

 upon short stalks or upon little projections of the wall of the conidio- 

 phore, or are completely sessile. The conidia, which are also colorless 

 at first, but become the same color as the conidiophore, are ovoid, 

 4X7//, with smooth, fairly thick walls. During germination, they 

 swell so as to be almost spherical in shape (Figures 39-41, Plate 12). 



Papulospora cinerea n. sp. 

 Plate 8, Figures 1-11. 



Mycelium white, septate, procumbent, forming a felted mass over 

 the substratum; bulbils steel-gray or slate-colored, somewhat spheri- 

 cal and flattened, 21-36 n in diameter, with three or four large angu- 

 lar central cells, and a layer of fairly regular cells forming a cortex, 

 but of the same color as the others; the primordium a spiral of one 

 or two coils. No conidia known. 



On gross culture in the laboratory, Cambridge, Mass. 



This fungus was found running over a gross culture in the Crypto- 

 gam ic Laboratories at Harvard University by Dr. Thaxter and has 

 been kept growing as a pure culture for more than ten years. It is 

 easily distinguished from any of the others by the steel gray or slate- 

 color of the bulbils, which are round, somewhat flattened in form, and 

 measure 21-36/i in diameter, in which respects they resemble those 

 of Papulospora sporotrichoid.es. The mycelium is white, procumbent, 

 forming a felted mass over the substratum, the slate-colored bulbils 

 being scattered among the white hyphal filaments, finally giving the 

 whole culture a bluish gray or steel-gray appearance. When young 



