The sporadic appearance of non-edible mushrooms in cultures of 
Agaricus campestris 
MICHAEL LEVINE 
(WITH PLATES 3-5) 
In studying the culture and development of Agaricus cam- 
pestris during the winter and spring of 1916-1917, I visited some 
of the largest establishments of commercial mushroom growers 
in the East and thus have had an opportunity to study the fleshy 
fungi, other than the commercial varieties of Agaricus campestris, 
which appear sporadically in the mushroom beds. A number of 
such types for this country have been recorded by Peck* and others, 
The appearance, in the beds of one of the largest mushroom 
growers in New York City, of great numbers of Panaeolus veneno- 
sus, a very poisonous mushroom recently described as a new species 
by Murrill,t furnished material for the special study of its phy- 
siological and toxicological properties and I have published my 
results along this line elsewhere.{ As this fungus seems quite 
dangerous I shall give here some results of observations made on 
the growth habits and describe another variety or ‘form in which 
it sometimes occurs. 
Panaeolus venenosus Murrill (PLATE 3, FIGS. I-8).—This species 
is of interest to mycologists, since up to the present time it has 
been found only in two widely separated mushroom houses in the 
vicinity of New York City, in beds spawned for Agaricus cam- 
pestris. The problem of its origin or occurrence in the wild state 
still remains unsolved. The plants studied were found in several 
different mushroom houses. In greenhouses which had been 
imperfectly darkened, better developed plants appeared, such as 
are shown in Fics.2 and 6. The plants grew in small fairy rings, 
mostly one to two feet in diameter, and in the darker mushroom 
houses were made conspicuous by the markedly | developed white 
* N. Y. State Mus. Bull. 157: 67-68, = IOTX; Bull. 150: 43: 1910. 
+A very dangerous mushroom. Mycologia 8: 186, 187. 1916. 
The physiological properties of two species of poisonous mushrooms. 
Torrey Club r7: 176-201, pl. r, 2. 1918. 
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Mem. 
