266 PROCEEDINGS OF THE AMERICAN' ACADEMY. 



history of the parasite is known." Before Biffen ('02) examined this 

 species, the only method of reproduction known was by its so-called 

 "chlamydospores" which at maturity consist usually of one large, 

 thick-walled, chocolate-brown, warty cell and three or more colorless 

 cells adhering closely to it. By the use of pure cultures Biffen claims 

 to have succeeded in obtaining not only the "chlamydospores," as 

 described by Berkeley and Broome, but also what he calls "spore 

 balls" (bulbils) and definite perithecia. 



The mycelium of Acrospeira is fine, colorless, procumbent, more or 

 less sparingly developed, and produces large numbers of reproductive 

 bodies, which, in their development and structure, are bulbils rather 

 than "chlamydo pores." They are so abundant that the whole 

 surface of a culture, which would otherwise be white, assume a 

 brownish aspect. The readiness with which these bulbils are pro- 

 duced makes it comparatively easy to trace their development, 

 which, in brief, is as follows: an erect lateral branch usually divides 

 into three secondary branches (Figure 18, Plate 5) each of which coils 

 up much like that of Papulospora parasitica, to be considered below. 

 They make about one to one-and-a-half coils and divide into three 

 cells by cross septa. The middle one of these three, as a rule, en- 

 larges rapidly, forming the functional spore (Figure 21, Plate 5) (the 

 central cell of P. parasitica), bu1 occasionally the end cell (Figure 20, 

 Plate 5) more rarely the third, is the one that functions in this respect; 

 while the other cells of the coil, ordinarily three or more in number, 

 grow less rapidly and eventually lose their contents, become colorless, 

 and adhere to the side of the large cell. If the marginal cells should 

 increase in number so as to enclose the large cell completely, there 

 would be practically the same condition as exists in P. parasitica 

 (Figures l(i, 17, Plate 5). In the present form, however, the large 

 cell becomes dark brown in color and develops a thick wall, which 

 eventually becomes warty, and measures 25-30 n in diameter. Fig- 

 ures 18-23, Plate 5, illustrate the stages in the development of this 

 bulbil. Thus in Acrospeira we have a structure that is only slightly 

 less complex than that seen in P. parasitica, a form in which many 

 imperfect bulbils can with difficulty be distinguished from some of 

 those of Acrospeira, their only difference being due to the absence of 

 a warty episporium. These bulbils were grown on various kinds of 

 sterilized nutrient material, and most of the experiments described 

 by Biffen were repeated. The culture conditions were varied with 

 regard to media anil oilier conditions of growth, in many of these 

 experiments, but more bulbils of the same kind were always produced 





