467 



pogonium is surrounded by numerous pollinodia, and fertilization takes 

 place in the same way as in the Discomycetes. In some species the 

 fertilized carpogonium contains only one ascus of an ovoid shape, which 

 encloses eight ascospores. In other species the carpogonium contains 

 several asci. 



The species of Enrotium, e. g. E. repens and E. (Aspergillus) glaueu-s, 

 agree in the essential details of their life-history with those of Erysiphe. 

 The mycelium is floccose, and may be found on the surface of the most 

 varied dead organic bodies. First are formed conidia in great abun- 

 dance in clusters at the apex of the conidiophores, and these reproduce 

 the mycelium so plentifully, that this fact, when coupled with the easily 

 satisfied requirements of the fungus in the matter of hosts, accounts for 

 its exceedingly wide distribution. On the same mycelium there arise 

 afterwards the sexual organs. The carpogonium is the end of a mycelial 

 hypha closely wound up in the form of a corkscrew, and provided with 

 several transverse septa one to each turn of the screw. From the lowest 

 turn there arise two tubes which grow up on the outside of the carpo- 

 gonium ; one grows more rapidly than the other, and reaches the top of 

 the carpogonium, with which it conjugates. This is the pollinodmm. 

 Other cells then grow out from the bottom of both organs and envelop 

 them. After fertilization the carpogonium divides into several cells, on 

 the branches which proceed out of which the asci, containing 8 spores, 

 arise. These ascospores germinate as in the other Erysiphece, and produce 

 a mycelium which bears first conidia, and again the sexually produced 

 fructifications perithecia. 



Suborder 3. TUBEEACE^E (fig. 1 C, p. 8). Eungi forming usually- 

 large subterraneous tuberous fruits, possessing a thick wall (peri- 

 dium) of pseudo-parenchyme, enclosing a dense mass of hypha), 

 among which the ascogenous threads form many asci imbedded in 

 the sterile threads. The mycelium is usually very small in com- 

 parison with the fructification, and conidia are known only in the 

 case of Penicillium glaucum. Illustrative Grenera : Tuber, Mich. ; 

 Penicillium, Link. 



Structure and Life-history. The mycelium of Penicillium glaucum 

 grows on almost all organic substances, and produces long chains of con- 

 idia on erect conidiophores in such abundance as to account for their 

 general presence in the air, and the appearance of the fungus on nearly 

 every suitable and accessible host. It is only, however, in darkness that, 

 like the other Tuberaceae, the fruits are formed. It is well known that 

 the conidia are not developed in darkness, and this formation of sexually 

 produced fruits in that condition (recently discovered by Brefeld) is a 

 further mark of the capacity of this fungus for distribution. The sexual 

 organs resemble those of JEurotium (above described) so closely that a 

 description is unnecessary ; but the development of the fructification after 

 the fertilization of the ascogonium is different from that of any other 

 Ascomycete. Shortly stated, the ascogonium after it has begun to ger- 

 minate is so hindered by the growth of the enveloping threads, that it is 

 compelled to rest for some time in asclerotioid state. When germination 

 is induced, however, by artificial means, the ascogenous threads are seen 



2 H 2 



