56 CULTURAL STUDIES OP SPECIES OP PENICILLIUM. 



per cent, typical, alkaline reaction when old, crystal drops. Levulose 3 per cent, 

 typical. Galactose 3 per cent, slow development, typical. Glycerin 3 percent, 

 t ypical. Potato starch 3 per cent, typical colony, crystal transpiration drops. Butter- 

 fat, typical colony, mycelial mass tinged violet. 



Milk, rich growth; curdling (0.25 per cent calcium chlorid added), in 8 days; diges- 

 tion, rather slow; color in milk, none. 



At :!7° ('., no growth, slowly green when cooled; check at 20 ° C., typical. 



PENICILLIUM COMMUNE n. sp. 



In examining numerous Petri-dish cultures made for the examina- 

 tion of milk by the bacteriologists of the Storrs Experiment Station, 

 large numbers of colonies of Penicillium have been studied. A very 

 large percentage of these colonies have a series of common characters 

 which are constant enough to mark out a species, or, perhaps better, a 

 group of races, between which differences are either minute or so 

 complicated by the occurrence of other races with overlapping char- 

 acters as to make their separation a matter of considerable doubt. 

 One of these has been selected as the basis of the following diagnosis. 

 This form is morphologically closely similar to P. expansum (see 

 figs. 1 and 19). It, however, lacks entirely the ability to form core- 

 mia and fails to discolor the substrata, but grows well in certain cul- 

 ture solutions which markedly restrain P. expansum, of which it might 

 possibly be regarded as a variety. From its abundance in the situa- 

 tions studied it has been designated as P. commune. 



Latin diagnosis. — Coloniis in gelatina vel agaro Solani tuberosi aut phaseoli cultis, 

 viridibus, demum brunneolis, in substrato late crescentibus, zonatis; marginis cres- 

 centis parte aeria ex conidiophoris, centri atque ex hyphis plus minusve floccosis 

 composita; reverso et substrato incolorato; conidiophoris plerumque 300/i raro usque 

 700/.( longis; fructibus conidicis 100-200/j longis, cum ramis alternatis et verticillatis 

 confertis, basidiis 8-9X3/Z cum apicibus brevibus acutis, catenas conidiorum longas 

 parallelis gerentibus; conidiis primum cylindricis vel ellipticis, demum globosis, 

 3-4/t diam., 5-6/* incrassatis germinantibus, levibus, viridibus, in catenis manentibus 

 submersis; coloniis in gelatina in parte lente liquefacientibus; odore mucidis. 



Habitat in lacte, caseo, etc., Storrs, Conn. 



Colonies in gelatin or in potato or bean agar, dull green, becoming brown when old, 

 broadly spreading, zonate, with broad white growing margin composed only of conid- 

 iophores, in the older parts becoming floccose masses of interwoven hyphae; reverse 

 of colony and substratum never colored ; conidiophores commonly 300/« or less in length, 

 sometimes up to 700// ; conidial fructifications commonly 100-200/i in length, compact 

 at base and broadening above, variously branching with branches appressed, and verti- 

 cils of conidiiferous cells 8-9 by 3/<, abruptly narrowed to produce conidia; conidia 

 cylindrical to elliptical and finally globose 3-4//, becoming 4-5/t or larger in germinat- 

 ing, smooth, green, persisting in chains in fluid mounts; colonies liquefy gelatin slowly 

 or partially, softening rather than producing clear liquid, alkaline in media without 

 sugar but acid with either cane sugar or lactose, having a strong " moldy" odor. 



Habitat, common in food, dairy products, etc., Storrs, Conn. 



