1891. Dimorphism of Hypocrea tiiberiformis . . 283 



peculiar structure of the apex of the asci in Epichloc and Hypo- 

 crella is not present in his specimens, or at least not represented 

 in the illustration. I first collected sterile forms of Hypocrea 

 tubcriformis B. & R. on Arundinaria at Columbia, S. C, 

 during the winter of 1 888-1 889. During the last two years 

 I have collected at Auburn, Ala., its sphacelia and ascigerous 

 stages. 



Stroma. — The stroma is subglobose, entire, lobed, or di- 

 vided, seated upon the reed or upon the leaf sheath and 

 fastened by a whitish mycelium, consisting of radiating, un- 

 dulate threads, which sometimes become tinged with yellowish 

 brown. It consists of two different strata when young, com- 

 posed of slender, compactly interwoven hyph.e. The outer 

 stratum is quite opaque, as shown in section, and yellowish. 

 It is connected with the inner white stratum by loose threads. 

 The whole is of a leathery or corky consistence. When ma- 

 ture a section shows three differently colored strata; an inner 

 layer, white, which is sometimes tinged with pink ; an inter- 

 mediate layer, light ochre; and an outer layer, cinnamon. The 

 intermediate layer is not quite so compact as the outer two. 

 After the stroma is dead it sometimes becomes black. 



Sphacelia STAGE. — The sphacelia stage occurs at Auburn. 

 Ala., in late spring. I first collected it May 10, 1890. The 

 conidiphores radiate from the surface, which they thickly 

 cover, and are needle-shaped, tapering gradually to a sharp 

 point where the conidia are borne. They measure 35-40^t 

 long by 2-3^ at the base. The conidia are oval or broadly 

 fusoid, inequilateral, hyaline, mostly continuous, but the larger 

 ones sometimes faintly one-septate. Size, 3- 5~ 4 X 7~ 10 ^- 



ASCIGEROUS STAGE. ' — The perithecia are sessile, or only 

 the rounded base immersed in the superficial part of the stro- 

 ma. They are subcylindrical, a little broader in the middle 

 than at each end, floccose, with loose white threads through 



\ • _ - *^-»« • A.K ~ « A 



which the cinnamon color shows. The apex is smooth and 

 resembles the apex of Epichloe typhina (Pers.) Tul. 1 he 

 ostiolum is distinct. They are about 1 millimeter long by 

 one-third of a millimeter in diameter, and stand on the stroma 

 singly or in groups of 3-4-20, or crowded over a large portion. 

 ^' " " - " * the bases of two, three or more 



1 hey are frequently branched, th 

 being joined and the cavities con 



'Mature in August and September. 



fluent below. 



