THE MYCOGOXE DISEASE OF MUSHROOMS AXD ITS COXTEOL. 5 



As previously suggested by Costantin and Dufour, it might be 

 supposed that these two forms of Verticillium belonged to two 

 distinct diseases. A specimen was found infected in the puffball- 

 like manner which had a rose-gray velvety covering and at the 

 same time a whitish woolly coating, on the lower part the Verti- 

 cilhum with small spores, and on the upper part Mycogone and the 

 Verticillium with large spores. There was a gradual transition from 

 the Mycogone and large-spored Verticillium to the small-spored 

 Verticillium. The conclusion is then drawn that there is one dis- 

 ease with two forms of Verticillium. This is an interesting fact, 

 since Costantin and Dufour by sowing the large-spored Verticillium 

 in suitable media produced Mycogone spores. The cultures were 

 at first drab in the center and white at the margin, finally be- 

 coming a color intermediate between light leather and umber. It 

 was impossible to cultivate the large-spored Verticillium alone, as 

 this form was always accompanied by the production of Mycogone 

 spores. 



When cultures were made irom the small-spored Verticillium of 

 puffball-like infected mushrooms, they remained permanently white 

 and only the Verticillium with small spores was produced. Never 

 could the small-spored Verticillium be made to take the characters 

 of the large-spored Verticillium. 



It is concluded that this parasite of the cultivated mushrooms 

 differs from Mycogone rosea and Mycogone cervina in habitat, size, 

 and color of the "chlamydospores," but that it is the species named 

 by Magnus (1906) Hypomyces perniciosus, although his description 

 was insufficient and he regarded the " chlamydospores " as being 

 hyaline, whereas this is only the case in immature spores, for they 

 rapidly become amber colored. The authors designate the species 

 as Mycogone perniciosa Magnus. 



Evidently Prillieux (1892), who believed the species to be Mycogone 

 rosea, later agreed with Costantin and Dufour in considering it 

 Mycogone perniciosa, for the sketch he presented before the Botanical 

 Society of France has been reproduced and designated as Mycogone 

 perniciosa (Prillieux, 1897). 



Delacroix (1900) described the disease "la mdle" as the most 

 important of the diseases of cultivated mushrooms, and ascribed it 

 to the fungus Mycogone perniciosa Magnus. 



Magnus (1906) discussed the work of preceding investigators and 

 concluded that the Verticillium agaricinum (Lk.) Cda. given by 

 Stapf (1889) as causing a serious disease of cultivated mushrooms 

 at Viemia is rather Mycogone rosea Lk. than Mycogone perniciosa 

 Magnus as given by Costantin and Dufour. However, the question 

 of specific identification is one which Magnus states requires further 

 study. 



