Qy. Dematimn pullulans de Bary. Isme A. Hog§an. loi 



II. Systematic Position of the Fungus. 



{a) Relationship to Cladosporium herbarum. 



De Bary(3) does not attempt to classify the fungus beyond 

 suggesting that it is probably nearly related to Fiimago or 

 Pleospora. 



Loew [loc. cit.) draws attention to the striking resemblance 

 between the uniseptate gemmae of Dematium and the spores of 

 Peyiicillium cladosporioidcs Fres. (= Cladosporium herbarum 

 Link), adding that they may be distinguished by the small 

 papilla at the base of the Cladosporium spore, which is absent 

 from the gemma; or, more surely, by their respective beha\'iour 

 on transference to fresh medium. Loew further remarks upon 

 the similarity of the resting mycehum of Dematium to the 

 h\-phae of Cladosporium. He did not, however, find any indica- 

 tion of a genetic relationship between the two forms, nor did he 

 succeed in obtaining anj' Cladosporium in cultures of Dematium, 

 nor vice versa. 



These observations have a direct bearing upon the \iew 

 since held bv various mvcologists that Cladosporium herbarum 

 and Dematium pullulans are different forms of one and the 

 same fungus. Thus we find that Saccardou^ gives the latter 

 as a stage of Cladosporium herbarum. In the words of Laurent (5), 

 however, "Cette opinion n'est basee, d'apres ce que m'a ecrit 

 le botaniste itahen que sur 1' aspect des filaments mycehens," 

 which cannot be considered as proof of identity. 



Laurent is nevertheless of the same opinion as the pre\-ious 

 author, and sets forth at length the reasons which led him to 

 adopt this \-iew. His e\-idence has been re\-iewed so thoroughly 

 by Planchon:6), however, that it seems best here to repeat in 

 outline the latter's criticisms and refer the reader for details to 

 the original work. 



Laurent bases his conclusions on the assertions : 

 (i) That he observed on several occasions aerial conidio- 

 phores of Cladosporium developing from the mycelium of 

 Dematium pullulans in culture, and 



(ii) That he obtained gro^^i:hs of Dematium from cultures of 

 spores of Cladosporium so\mi in tubes containing beer^vort and 

 placed in sunhght, while similar tubes retained in the dark gave 

 rise to Cladosporium. 



He also figures a conidiophore of Cladosporium in organic 

 connection with a h\-pha of Dematium bearing spores (Fig. S, 

 p. 585); and he infers that Dematium pullulans is "un etat 

 afi'aibh du Penicillium cladosporioides." 



Planchon examines and questions the purity of Laurent's 

 cultures. He comes to the conclusion that the latter was in 



