Nn.MI N< I.ATCKI.. 23 



In the work here reported nitrogen \\ r as added as sodium nitrate, 6 

 grams. Parallel experiments in which monopotassium phosphate 

 (KH.I'Oy. which gives a perfectly clear solution of a strongly acid 

 reaction, was substituted for dipotassium phosphate, K.I I P( ),, gave 

 no advantages in cult n re to offset the advantages of a neutral medium 

 except the disappearance of the traces of precipitated magnesium 

 phosphate. The availability of carbon in any organic form can be 

 tested readily in this solution. Solidified media are obtained by the 

 addition of agar. 



NOMENCLATURE. 

 THE GENERIC NAME. 



The generic name, PenidUium Link, is held -in this paper in its 

 hyphomycete sense to designate all species which continue to propa- 

 gate themselves for an indefinite number of generations by penicil- 

 late asexual fructifications. Such grouping does not imply the 

 author's belief in the phylogenetic relationship of all such forms. 

 The penicillate type of fructification is a definite character which 

 binds together in this way into a "form-genus" a large number of cos- 

 mopolitan and omnivorous saprophytes, very few of which are 

 known to produce sexual fructifications. Within this heterogeneous 

 group, several series of forms possessing particular groups of char- 

 acters have been separated and generic names have been based by 

 some workers upon such segregation. Wehmer 28 founded the ^enus 

 Citromyces upon two such species causing citric acid fermentation in 

 sugar media, with its morphological basis in the presence of a single 

 whorl of conidia-bearing cells at the apex of the conidiophore. Fur- 

 ther .study slows that the presence of this character alone would 

 group together forms not so closely related to each other as to other 



species of PeniciUium lacking this character. It seems best, there- 

 fore, to use the name l\ iiirillium to designate the entire group and 

 leave further investigation to establish permanent genera when 

 really genetic relationships shall have been discovered. 



NOMENCLATURE OF SPECIES. 



In considering the actual problem of nomenclature of species 

 several positions may he taken. It is not difficult to find published 

 descriptions of single species in this genus which are sufficiently 

 indefinite to include a large percentage of all the know n species. A- ;i 

 rule, the morphological character-, of the various forms under culti- 

 vation would not exclude them from half a dozen of the older 

 species so far as current descriptions go. hi many cases there would 

 not, however, he the leas! reason for the adoption of one name in 

 preference to another. Shall the investigator adopt for his material 



