Thom: Penicillium Luteum-Purpurogenum Group 135 
under some conditions of culture falls definitely within the Core- 
mium group as used by Wehmer. Under other conditions it be- 
comes a simple Penicillium.^ P. expansum Link, observed upon 
a rotten apple, is usually typical for the genus Coremium, but 
when transferred to culture media becomes a Penicillium again, 
which under many cultural conditions shows no sign of coremia. 
Sopp'^ has also definitely broken the penicillately fruiting or- 
ganisms into several genera upon n orphological lines. 
The difficulties encountered in the use of either plan suggest 
the desirability of continuing the general use of the name Peni- 
cillium for the entire group until definite natural lines of cleavage 
can be established. 
Penicillium, in the narrowest sense, as discussed by Wehmer, 
includes those forms which produce green mold surfaces consist- 
ing of a large number of separate conidiophores. Within this nar- 
rowest group he finds also natural cleavage lines which perhaps 
represent real relationship. He has pointed out one such natural 
group and suggested that it be called the Verticillatae. This sec- 
tion and a si igle series within this group form the subject of this 
paper. In the past ten years about fifteen members of this series 
have been collected from widely separated regions. Some of them, 
P. luteum, P. africanum, P. pinophilum, and P. purpurogentim were 
already named and described without indication of relationship. 
Several, for example, P. africanum and P. purpurogenum, among 
named forms, are closely enough related to make separation 
troublesome even to the describer.® When several other members 
of the series are added, the description of each in terms which 
will insure identification by the next worker becomes more diffi- 
cult, perhaps impossible. Descriptions and figures for a series of 
these forms were prepared, laid away, then reread, and compared 
along with fresh cultures and accumulated cultural data. Some 
of these forms have been kept in continuous culture for about ten 
years. They maintain the individuality of old friends. Such 
strains are well established biological entities but to draw a tech- 
8 Thom, C. 1 . c. 
’ Sopp, O. Johan-Olsen. Monographic der Pilzgruppe, Penicillium, etc. 
Videnskapsselskapets Skrifter I. Mat.-Naturv Klasse 1912, No. ii, Chris- 
tiana, 1912. 
* Doebelt, H. Ann. Mycol. 7 (1909), No. 4, pp. 315-338. 
