THE GENUS ASPERGILLUS. 



33 



serve to define more clearly the object examined. The fact that 

 simple and branched sterigmata are found associated in certain 

 species (A. spurius, 

 A. candidus, A. 

 ostianus) which, 

 therefore, consti- 

 tute intermediate 

 types is not alto- 

 gether favourable 

 to the subdivision 

 of a separate genus, 

 Sterigmatocystis. 



Up to the pre- 

 sent, ascospores in 

 the form of small 

 globular nodules 

 (Fig. 165) measur- 

 ing about 60-300 p. 

 in diameter, have 

 only been definitely 

 found in about 5 

 species (A. glaucus, 

 A . fumigatus, A . 

 Rehmii, A . nidu- 

 lans, A. pseudocla- 

 vatus), but more 

 will probably be 

 discovered in time, 

 in which event the 

 form of these spores 



may be utilised as a basis of classification. Meanwhile it seems pre- 

 ferable to postpone the division of the genus Eurotium (A. glaucus) 

 and to retain the conidiophores as a generic characteristic. In 

 most cases the perithecia are fragile capsules, with thin walls, and 

 yellow, dark red, or even black in colour (A. glaucus, A.pseudo- 

 davatus, A . Rehmii, A . fumigatus), which, in the last two instances, 

 is enclosed in a shell formed of specially modified, coloured, thick- 

 walled, swollen hyphse, but in the others is naked. A shell is also 

 found in A. nidulans, but here the ascospore is tougher, the asci 

 (sclerotia), surrounded by a dark, stratified skin, being developed 

 later. Similar naked or sheathed sclerotia, which, however, are 

 sterile, were observed by WILHELM (I.) in the case of A. niger, 

 A. ochraceus and A.flavus. The development, chiefly through the 

 implication and fusion of morphologically equal hypha, as in A. 

 Rehmii and A. ochraceus, and also the character^ the asci and 

 spores, will be found compared in the description of the various 

 species later. In A. glaucus the development proceeds from a 

 single filament, in A. nididans from two. The ascospores are 

 VOL. IT : PT. 2 U 



FIG. 164. Conidia of Aspergillus. 



All of approximately equal magnification, showing the 

 differences in form aud dimensions. A. glaucus (i), A. 

 fumigatus (2), A. niger (3), A. clavatus (4), A. Tokelau 

 (5), A. varians (6), A. Onjzce (7), A. Wentii (8). Magu. 

 about 1000. (Original.) 



