199] PARASITIC FUNGI— STEVENS 33 



On unknown host. 



British Guiana: Tumatumari, July 8, 1922, 45. 



The colonies of this fungus are approximately circular, Fig. 109, the 

 mycelium radiating from a central point of origin, which point is usually, 

 perhaps always, occupied by a dense aggregate of mycelium (the umbo), 

 (Figure 80), appearing somewhat like a stroma but always devoid of cavi- 

 ties or spores; though on crushing, the mass is seen to be filled with coarse 

 amorphous grains not found elsewhere with the fungus. The mycelium 

 reaches out from this point to a distance of 1 tol.5cm.and consists, near the 

 center, of thick ropy strands composed of many agglutinated threads. 

 Toward the edge of the colony these strands become smaller, ending in 

 single filaments. (Figure 87). In the lacunae between the ropy strands 

 many thin branches of this mycelium wander. The mycelium appears of 

 somewhat gelatinous texture, particularly evident in the young thin threads 

 and where adjacent strands adhere firmly. 



Near the center of a colony are borne from few to several dozen stromata 

 as described above. These always arise in the lacunae between the ropy 

 strands and are produced by the massing of the fine gelatinous threads. 

 The stroma in its very young stages appears to be nearly of its full, mature 

 diameter though very thin and almost translucent and when very young 

 it shows a full compliment of ostioles. Later development consists chiefly 

 in the increase in thickness, color and in the growth of the numerous setae, 

 together with internal development. On crushing the numerous asci and 

 spores are found surrounded with quantities of gelatinous paraphyses. 

 The central umbo lifts readily from the leaf surface and appears to be not at 

 all, or at most very slightly connected with it. Under the umbo there is 

 always a nectary gland, strictly circular, brown, about 385m in diameter. 

 (Figure 80). Several other species of fungi are found occupying these glands, 

 but no other bore spores. It seems probable that the glands serve as 

 necessary starting points for the growth of the colony. The same relation 

 to glands was noted on the unknown host No. 45, also on the Coccoloba, 

 No. 40. 



While the fungus on Coccoloba in the microscopic structure appears 

 to be identical with that on other hosts, microscopically it shows some differ- 

 ences in that the colonies are very much smaller, usually not more than 

 0.5 cm. in diameter and the number of stromata is less. Evidently the 

 Coccoloba glands do not afford as good conditions regarding nutriment 

 as does Hirtella. This fungus in its perithecium superficially resembles 

 the genus Polystomella of Spegazzini but it cannot be regarded as even 

 of close kinship with that fungus because its perithecium is not radiate; a 

 character which is attributed to Polystomella by all who have worked with 

 the genus (cf. Arnaud'^ PL 23 figs. A-K, Theissen,'^ Tab. 6 fig. 4, 13.) and 

 " Amaud, G. Les Asterinees, Ann. de I'EcoIe nat. d'Agric. de Montpellier, 1918. 

 " Thcissen, F. Uber Polystomella, Microcyclus u. a. Ann. Myc, 12:63, 1914. 



