82 CULTURAL STUDIES OF SPECIES OF PENICILLIUM. 



result of comparative culture is found in the separation of the series 

 into groups of races or species which resemble each other closely in 

 their metabolic activities. Part of these experiments are tabulated 

 in Tables 2, 3, 4, 5, and 6, and will be discussed in the following 

 sections. 



Since the complex composition of the media in common use for 

 cultural work makes the analysis of the data obtained impossible, 

 it was first necessary to determine the reactions of these species to 

 some of the individual substances of which these media are composed. 

 It has already been noted that gelatin alone in distilled water sus- 

 tains growth in the large majority of the species of this genus. 

 These cultures in certain species lack green color, which, how- 

 ever, becomes present on using the peptones and sugars added to 

 gelatin in most formula?. Such media are still too complex to make 

 close analysis of results possible. 



Man}' of the determinations given were made in duplicate and in 

 some cases the entire series was repeated one to several times. In 

 inoculating cultures for this work conidia were transferred to the 

 tubes in large numbers, so that their presence could be detected by 

 examination with a lens. Where species failed to grow, the doubts 

 of inoculation were commonly dispelled by the addition of cane 

 sugar, which permitted the conidia to develop normally if present 

 and still viable. The presence of germinated conidia upon the sur- 

 face of a medium is good evidence of proper inoculation. The data 

 given are believed, therefore, to represent with a fair degree of 

 accuracy the comparative cultural reactions of the species used. 



In reporting these series of comparative cultures, the data have 

 been tabulated as far as possible for convenient comparison of the 

 relative activity of the different forms. (See tables beginning on 

 p. 98.) The names as far as determined are given, together with the 

 cultural number, in Table 1 . In the remaining tables the numbers 

 are repeated without the names. In studying the tables a reference 

 to cultural numbers will quickly locate the forms discussed. 



CULTURES IN DISTILLED WATER. 



To determine the possibilities of growth from food stored in the 

 conidia, cultures were made in distilled water. Of forty-four strains 

 under cultivation but six showed clearly descernible germination. 

 None produced more than germ tubes hanging down into the fluid. 



a This work was carried on in cooperation with Mr. A. W. Dox, who has studied the 

 metabolism of the species concerned with cheese ripening (P. camemberti and P. 

 roqueforti), as well as a few other species, under many conditions of culture, while the 

 writer has conducted comparative studies of a large number of forms under more 

 limited cultural conditions. All chemical questions arising throughout this work 

 have been passed upon by Mr. Dox. 



