24 CULTURAL STUDIES OF SPECIES OF PENICILLIUM. 



a name previously used when he has little or no reason to believe that 

 he has the organism originally described under that name ? Granting 

 the apparent impossibility of contradiction, he might find it a safe 

 practice. If, however, contradiction should arise, the position 

 becomes entirely indefensible. In case there- is a fair probability that 

 the forms are identical, the use of the old name may be justified per- 

 haps without direct proofs. The alternative position calls for the 

 complete description of the form studied and its distribution in cul- 

 ture to different centers of cultural work under a new specific name 

 associated with this definite material and description. It can not be 

 contended that these organisms are new to science, for it is entirely 

 possible that certain of them have formed the basis for already pub- 

 lished descriptions. This course can be justified by the contention 

 that such publication applies to definite material, available for 

 examination, culture, and comparison by others, and that there is less 

 probability of confusion from such publication than would ensue 

 from the use of names long published, without any real evidence of 

 the identity of the organisms with those originally studied. After 

 careful examination of all material available and consultation with 

 many workers in closely similar fields, new names are attached to 

 such forms as by continued cultural study appear to be sharply 

 marked species but not identifiable by older descriptions. 



The name P. glaucum is not used. Careful examination of literature 

 and of cultural material from several sources, together with confer- 

 ences and correspondence with investigators in numerous laboratories, 

 does not afford evidence as to what form was originally used by Link 

 or even secondarily by Brefeld 2 under this name. The name as used 

 at present seems to be applied collectively to the common green 

 forms which under examination are quickly found to be not one but 

 several species. Further study may give some indication as to 

 where the name really belongs, but until that time there is little 

 profit in applying it to any particular form. It might, perhaps, be 

 withheld until some worker succeeds in repeating Brefeld's classic 

 studies in ascus production, and then applied to the form so found. 



The present paper is not intended to be a monograph of the genus. 

 It is presented as a report covering several thousands of cultures 

 of a group of common forms, in the hope that the descriptions and 

 key offered may be useful to others. The author has included 

 studies of as many authenticated cultures of the more recently 

 described forms as it was possible to secure. The verified cultures 

 secured have already been listed. Much assistance and advice were 

 freely given by Dr. C. Wehmer. On the other hand, it was impossi- 

 ble to secure cultures of the species recently described by Oude- 

 mans, 17 or those listed by Dierckx; 5 and one recently described by 

 Peck 18 also appears to be lost. No claim to completeness can be 



