98 A MANUAL OF THE ASPERGILLI 



isolated from nature, and since no evidence has been presented indicating 

 that these larger forms arise directly from the smaller and more common 

 forms. While it is true that conditions can be altered so that A. giganteus 

 cultures suggest A . clavatus, no one has yet demonstrated that the reverse 

 can be accomplished. 



Group Synonyms 



The following names have been proposed for specimens belonging to this 

 group but without adequate data to warrant recognition as valid species : 



A. clavellus Peck, in N. Y. State Mus. Nat. Hist. Rept. 34: 49, PI. 2, figs. 1-5. 

 1881. Described from cooked squash in New York State. No data is presented which 

 would warrant separation of this form from A. clavatus Desm. 



A. westendorpii Sacc. and March, in Rev. Mycologique 7: 149, 1885, was listed 

 from cow dung. Correctly assigned to A. clavatus by Lindau, in Deutsch. Krypt. 

 Fl. Pilze 8: 152. 1907. 



A. fusco-cinereus Ellis and Morgan was the name attached to Morgan's jacket 

 No. 674, showing a very small, clavate aspergillus which has not been collected again, 

 hence never cultivated. It was probably some member of this group. 



A. pseudo-clavatus Purjewitch, in Schrift. Naturforsch. Gesell. Kiev 16 (2): 309, 

 pi. 12, 1900; see also Sacc. Syll. 16: 1028. The organism in culture was reported as 

 having both primary and secondary sterigmata in a small-sized "clavatus" type of 

 head, and perithecia with ascospores which were not adequately described. Until 

 somebody finds this organism again and reports its cultivation and more complete 

 description, it will remain doubtful. (See Thorn and Church, The Aspergilli, 

 p. 100. 1926.) 



Occurrence and Economic Importance 



Members of the A . clavatus group are quite common in soils and decom- 

 posing materials characterized by a comparatively high nitrogen content. 

 They appear to be common upon the dung of various animals and in the 

 writers' experience have been isolated repeatedly from that of chickens. 

 While the subject has not been adequately investigated, it is probable that 

 the ability of members of this group to withstand strongly alkaline condi- 

 tions enables them to operate successfully as agents of decomposition in 

 situations where almost all other fungi are eliminated. 



Antibiosis 



Certain strains of A . clavatus produce substances in the substratum which 

 are capable of destroying Staphylococcus and other microorganisms. Such 

 activity was first reported by Weisner in March 1942 (Nature 149: p. 356) 

 and subsequently by Waksman, Horning, and Spencer in August of the 

 same year (Science 96: p. 202). To the active substance the latter investi- 

 gators assigned the name clavacin and noted that it appeared similar to, if 

 not identical with, that studied by Weisner (1942) to which the designation 



