328 A MANUAL OF THE PENICILLIA 



Colonies on steep agar essentially as above but more heavily sporing, 

 darker in color near castor gray (R., PI. LII), marked by fairly prominent 

 but very narrow concentric zones, and producing less abundant exudate; 

 penicilli as above but generally somewhat larger and more regularly 

 branched. 



Colonies on malt extract agar somewhat lighter in color, of looser-tex- 

 ture, heavy sporing (fig. 88B), with conidiophores long, up to 400 or even 

 500m, arising primarily from the substratum and bearing comparatively 

 large and strongly divaricate penicilli, consisting of few to several diverg- 

 ing, fairly definite columns of conidia up to 100/x in length. 



The characterization given is drawn primarily from cultures XRRL 

 915 and 917. NRRL 915 was received by Thom in 1922 from the Rainier 

 collection in Paris bearing the label "Penicillium riigricans" (nomen nu- 

 dum). NRRL 917 was subsequently received from Prof. Westerdijk 

 at Baarn as P. echinaturn Dale. The two cultures are in fact identical, 

 and for reasons explained by Thom in his Monograph (1930), the latter 

 should be regarded as a sj^nonym of P. nigricans (Rainier) Thom. Strains 

 duplicating these are not infrequently isolated from soil. 



The use of the name Penicillum echinaturn bj^ Rivolta in 1873, invali- 

 dates Miss Dale's use of it in 1926 for this organism. The name P. echinu- 

 latum Dale appears in Biourge's "Liste Onomastique" but not in D.ale's 

 papers. It is not explained. 



Oilman and Abbott (1927, p. 293) assigned the name Penicillium echina- 

 turn Dale to Thom's description of the green members of the sub-section 

 Divaricata in the series published by Pratt (1918) as the "Soil Penicillia". 

 That description was purposely made broad enough to cover a series of 

 forms now placed in P. janthinellum but which he did not wish to attempt 

 to describe at that time. It did not, however, include the forms with glob- 

 ose, rough, conidia now under consideration. 



Forms presenting essentially the cultural and morphological picture 

 described above occur abundantly in soil and upon organic materials un- 

 dergoing slow decomposition. Such forms may vary in specific details. 

 In some cases they fail to show- the characteristic golden orange coloration 

 of colonies in reverse ; in other cases sporulation is reduced and the strains 

 appear more nearly floccose than the species description would indicate; 

 while in still other cases the conidia, while roughened, are not conspicu- 

 ously echinulate as in completely typical representatives of the species. 

 All of these forms, however, produce conidia of some dark gray color; all 

 produce conspicuously divaricate penicilli; and no satisfactory lines of 

 separation warranting species recognition seem to exist between them. 

 Zaleski (1927) examining Penicillia isolated from the forest soils of Poland, 

 encountered some of these forms, regarded them as distinct, and described 



