THE SPECIES OF THE GENUS PENICILLIUM. 335 



structure compact, not woolly, conidia abundant. Under certain 

 conditions, though not very regularly, the species forms small, 

 hard, spherical to nodular sclerotia, resembling grains of sand in 

 size (0.1-0.8 mm. in diameter), and gradually forming asci, after 

 a period of repose, by resorption of the tough central tissue. 

 The closely crowded, globular to ellipsoidal asci (12-15 by 8-10/1) 

 fall apart eventually, so that when ripe (after about 7-8 months) 

 the interior of the organ, which is surrounded by a stratified 

 skin (2-3 layers), is full of free, pale yellow, ellipsoidal spores 

 (5~6 by 4-4.5^1). In germination, the individual spores, which 

 have a longitudinal groove and 3-4 transverse ribs, throw off the 

 two halves of the epispore. According to Brefeld's earlier 

 reports, the sclerotium is developed from two special hyphse (the 

 ascogonium and pollinodium) by a kind of fructification process, 

 the asci being then formed as lateral shoots from the ascogonium. 

 ZUKAL (II.), on the other hand, describes the formation of the 

 sclerotium as resulting from the fusion of two equivalent, simple, 

 vegetative hyphse, and has observed the asci developing from the 

 filaments growing out from the wall of the hollow sclerotium into 

 the interior cavity of same. 



It seems evident, from the varying dimensions of the conidia, 

 and especially from the reports on the limits of temperature, that 

 the P. glaucum described by various authors was not always one and 

 the same fungus. Only the dimensions given for the conidia by 

 SCHROTER(!.), namely, 2-3 p, and by WEHMER (XXIII.), namely, 

 3 ^u, agree closely with the figures given by BREFELD (II.), 

 SACCARDO (III.) reporting them as measuring 4 p, Lindau 3-4 p. 

 (globular or ellipsoidal conidia), and STOLL (I.) 3.8-4.3 p. The 

 latter worker in particular seems to have had before him a very 

 different form, with round spores, since it thrives as well at 37 0. 

 as at 8 0., the maximum temperature being even above 40 C., 

 whereas, as a matter of fact, most of the forms of this class die 

 off completely at 37C. Others have found the minimum and 

 maximum temperatures for P. glaucum as 1.5 2 C. and 

 33~35 Q- respectively. If Grawitz formerly habituated the 

 fungus to temperatures of 38-4o C., and then made successful 

 inoculations on animals, lie could hardly have been working with 

 a form of P. glaucum. The form grown by STOLL (I.) gave a 

 pure white instead of green vegetation on agar-agar after several 

 re-inoculations, thus producing a white form, analogous to 

 P. candidum, Link, which, however, reverted to the green form 

 and produced the normal conidial pigment, when transferred to 

 ordinary media. Actual proof is lacking in support of GUEGUEN'S 

 assumption (II.) that the species known as P. ^glaucum varies 

 considerably in the form of its conidia, and that a form with 

 round spores can pass over into a form with elongated spores. 

 This is, moreover, very unlikely, and the probable explanation is 

 that similar but really different species were present in the mixture, 

 VOL. ii : PT. 2 Y 



