94 



Journal of Agricultural Research 



Vol. XHI, No. 2 



storage. In this connection many studies of its activities have been made. No ade- 

 quate comparative study has yet shown the nature of the differences observable 

 between these strains. Until such study has been made the separation of this series 

 into species or varieties would necessarily be valueless. 



No. 363 and 712 appear to be close to P. viridicatum Westling. The original of West- 

 ling 's description was found in Sweden on roots and moldy twigs. A closely related 

 strain from soil has since been sent us from England by Miss Dale, and similar strains 

 from soil have come to us from widely separated States. 



No. 502 is an Aspergillus for which we have yet no name to offer. This again appears 

 in more than one series of soil cultiu-es. 



Among the very difficult Penicillia, No. 480 and 621 are probably identical members 

 of the blue-green series; No. 452.3 suggests P. pulitans Westling. But by far the 

 most interesting series in this collection is designated in Table III, the soil series, 

 including No. 401, 447, 452.1, 597, 598, 601, 604, 606, 629, 630, 675, and 756. This 

 lot of forms presents a series of characters which have come up repeatedly in studying 





'■>■: <?i^' 



Fig. 3. — Penicillium soil series (strain 89): Colonies pale green, velvety at border, but more or 

 in center with under side of mycelium rose to dark-red, conidia becoming globose, 2 to 3 m 

 Drawn by Dr. Charles Thorn. 



less floccose 

 in diameter. 



the fungi of the soil. Similar forms have been received from Miss Dale, of England, 

 from the soil bacteriologists of the United States Department of Agriculture, from 

 Connecticut, and from New Jersey, and from other sources. Such forms seem to be 

 found fairly constantly in soil cultures, but are not common in studies of foods and 

 feeding stuffs. 



Attempts to identify these forms by published descriptions were not satisfactory. 

 Descriptions and drawings were prepared for a series of them, but these when critically 

 compared demonstrated the close relationship of the organisms under consideration. 

 It seemed very doubtful whether separation by such descriptions could be considered 

 practical. The alternative is a group description drawn in broad enough terms to 

 indicate the characteristic structure of the group w^ith the range of variation observed. 

 The following description is proposed: 



Colonies in Czapek's solution agar white to gray, gray -green, pale-green, or pale 

 bluish green, when old becoming various shades of gray and brown, spreading slowly 

 but broadly with usiially a wide sterile margin throughout the growing period and 



