46 



CULTURAL STUDIES OF SPECIES OF PENICILLIUM. 



cells continuous with conidiophores 12-15 by 4/i tapering to slender sterigmata. Co- 

 nidia somewhat pear-shaped, slightly tuberculate at apex, with broad base, 6.5-7.5 by 

 7.5-9/i, in mass light brown to chocolate; at first smooth, then with thick tuberculate 

 walls, viable for many months, germinating by a single tube from the thin center of 

 the broad base into a bulbous enlargement from which mycelial hyphae about 2/t in 

 diameter arise. Mycelium very thin walled, narrow cells of varying length. Colonies 

 liquefy sugar gelatin and give a strong blue reaction in litmus media, but grow very 

 tardily, if at all, in potato or bean agar. Grows very rapidly upon neutral or alkaline 

 media, but very slowly or not at all in media acid to litmus. Digests milk. Refused 

 to grow after repeated inoculation into sterilized apple. Spores which refused to 

 germinate in the agar media used grew immediately when transferred to any of the 

 gelatin media. 



Cosmopolitan, forms characteristic chocolate patches on Camembert cheese. Se- 

 cured from numerous brands of cheese and common in the laboratories of this station. 



Fig. 12— Pen icillium brevicaule Saceardo: a, conidiophores and simple conidial chains with spores still 

 smooth (X 900); &,/, more complex conidial fructifications (X 900); c, two young conidial chains, show- 

 ing thick walls of spores (X 1,400); d, c, conidia after becoming echinulate (X 1,400); g, h,j, sketches of 

 forms and habit of conidial fructifications (X 140); g from an old cluture, sessile or almost so; h and j 

 show trailing hyphae and a rope of hyphae with lateral conidiophores; k, germinated conidium where 

 the old spore wall lies empty beside the growing cell (X 1,400). 



The author does not believe that this species is closely related to 

 other species of this genus, but since it has been placed here by a 

 very liberal interpretation of descriptions it may perhaps remain 

 under this name until someone finds out its real affinities. The two 

 forms which follow as varieties are found in the same habitat, show 

 closely similar morphology, and give almost identical physiological 

 reactions. Their designation as varieties of P. brevicaule may there- 

 fore be justified, though one at least (var. glabrum) seems separate 

 enough to warrant proposing for it a specific name. 



CULTURAL DATA. 



Color, conidial surfaces clay-yellow to chocolate; reverse of colony, 

 colorless; color in media, none. 

 Odor, ammoniacal, used as a test for arsenic (Gosio et al.). 



mycelium 



