Nov., 1922] LEVINE LAMELLAE IN AGARICUS CAMPESTRIS 
Tubaria furfuracea. Although Miss Walker was unable to find stages 
early in the development of Pliiteiis admirabilis , she contends that in this 
form the primordium of the hymenophore is exogenous in origin and later 
becomes endogenous, a claim similar to that made by R. Hartig in 1874 for 
Armillaria mellea which was later corrected by Atkinson (19146^). 
The studies reported by Atkinson and his students were made on 
material collected in the field. Specimens were fixed generally with chrom- 
acetic and picric-acid solutions. In no case so far as reported was the 
history known of the group of buttons studied. The assumed ages were 
generally based on size rather than on actual knowledge of the time of 
appearance of the button. 
Adams (1918), in studying the development of Schizophyllum commune 
grown in artificial culture media as well as of plants collected in the field, 
found, contrary to all observations previously made by other investigators 
on this form, that the hymenium primordium of this plant arises endoge- 
nously. He shows clearly that there is no general annular gill cavity formed 
into which the young gills develop by downward growth, but that a series 
of successively formed endogenous . gill chambers are produced which 
become ultimately the spaces between each pair of adjacent gills. These 
results agree entirely with my observation on the method of origin of the 
gill cavities in Coprinus. Adams concludes that the gills are essentially 
hymenium-bearing plates between schizogenously arising gill cavities. 
Material and Methods 
Since 1913 I have been studying cytologically the development of a 
number of species of agarics grown in controlled cultures. I have worked 
especially with Coprinus ephemerus, C. stercorarius, and Agaricus campestris 
var. Bohemia and a white variety possibly Columbia, spawn of which was 
bought from an American spawn producer. The species of Coprinus 
studied were selected, first, for the ease with which they may be grown 
under laboratory conditions on their natural substratum as well as on agar; 
second, for the rapidity with which they grow and develop from spore to 
mature carpophore; and third, because of the relatively small number of 
gills. Spores of Coprinus ephemerus and of C. stercorarius were sown on a 
variety of agar media. The most favorable was made of a horse-dung 
decoction. Within seven to ten days after inoculation a great number of 
young carpophores made their appearance on this medium. These cultures 
grow best at a temperature of from 20°-25^ C. Carpophores were produced 
more abundantly during the winter and spring months than during the 
summer. They were more nearly normal in appearance when grown in 
semi-darkness. 
It was found impracticable to grow Agaricus campestris in sufficient 
quantity in vitro. My cultures were grown in a mushroom cellar in the 
greenhouses of Columbia University. The space available, however, was 
