Buchanan : A New Species of Thyrococcum 



3 



the beginnings of sporodochia may be found in great abundance 

 within twenty-four hours. 



The spores are spherical, rarely becoming somewhat irregular 

 by the distension of one or more cells. They are 10-25 /x, usually 

 about 20 /x, in diameter, brown when young, when mature opaque, 

 shining, coal-black, and waxy. The mature spores are multi- 

 septate. The septa begin to appear when the spore is two thirds 

 grown, but the mature spores are too opaque to reveal the internal 

 structure readily, although in a few individuals the septa may be 

 seen. There can be no doubt of their septate character after an 

 examination of Plate 34, figures 4 to 7, and particularly Plate 35, 

 figure 2, which illustrates the many tubes which issue from a 

 germinating spore. As suggested by Lindau in the quotation 

 above, we may refer this species to the genus Thyrococcum 

 rather than Epicoccum on the basis of the septation of its spores. 

 It is possible that several other species with occasionally septate 

 spores that have been described as Epicoccum belong to Thyro- 

 coccum. The septa in some cases radiate from the center and 

 give the spore the appearance of a musk-melon with longitudinal 

 grooves. More frequently, however, they are placed irregularly. 

 The surface of the spore is areolate and somewhat tuberculate. 

 A diagnosis of the species follows. 



Thyrococcum humicola sp. nov. 



Hyphis sterilibus, decumbentibus vel assurgentibus, in agar 

 hyalinis, in aere fuscis, roseis vel brunneis, multis ramosis, 

 septatis ; sporodochiis orbicularis sparse gregariis vel separatis, 

 raris confluentibus, 50 to 500 fi diam., fuscis ; conidiis, sphaericis 

 vel raris irregularis, multo-septatis, dictyosporis, 10-25 /x in diam. 

 non stipitatis, reticulars, verrucosis, primo atrobrunneis denique 

 nigris. 



Hab. in dextrose agar pulvere terrae humosae infecta. 



Bacteriological Laboratory, 



Iowa State College, Ames, Iowa 



