1915-] DEVELOPMENT OF AGARICUS RODMANI. 337 



of the lamellae is of renewed interest since it has recently been 

 stated that one of the problems yet to be worked out in the Agarica- 

 cese is the origin of the lamellse.^^ The evidence presented in sup- 

 port of this sweeping, and rather surprising statement, is made, so 

 far as we can judge, on the basis of an investigation of Coprinus 

 micaceus. It carries with it the implied charge that all of the ob- 

 servations and statements in regard to the origin of the gills, cov- 

 ering a period of more than half a century, are incorrect. In the 

 case of my own work on Agarictis campestris,^^ Armillaria mellea,^^ 

 Lepiota clypeolaria,^' Agaricus arvensis^^ and A. conitulus it can be 

 most positively reaffirmed that the lamellse originate as described, as 

 downward, radial growths of the level palisade portion of the hymen- 

 ophore. The evidence was so clear in these examples that at the 

 time of the study it did not seem desirable to present full series of 

 " tangential " sections of the different stages in the origin of the gills, 

 particularly as the method of origin agreed in all respects with that 

 described in more than a dozen different species in earlier works. 

 The present study of Agaricus rodmani was undertaken, not only 

 for the purpose of examining into the significance of the double an- 

 nulus, but also for the purpose of examining the different stages in 

 the organization of the hymenophore primordium, the level palisade 

 stage, and the origin of the gills, in a species closely related to 

 Agaricus campestris. It is very clear that the present study has 

 fully confirmed the earlier statements with reference to the origin 

 of the lamellae. Material has also been grown, and the young stages 

 obtained for sectioning in the following commercial forms of 

 Agaricus: A. campestris varieties bohemia and alaska, and A. " vil- 

 laticus." 



34 Levine, M., " The Origin and Development of the Lamellae in Cop- 

 rinus micaceus," Am. Jour. Bot., i, 343-356, pis. 39, 40, 1914. 



35 Atkinson, Geo. R, The Development of Agaricus campestris," Bot. 

 Gas., 42, 241-264, pis. 7-12, 1906. 



36 Atkinson, Geo. F., "The Development of Armillaria mellea," Myc. 

 Centralb., 4, 113-121, pis. i, 2, 1914. 



37 Atkinson, Geo. F., " The Development of Lepiota clypeolaria," Ann. 

 Myc, 12, 346-356, pis. 13-16, 1914- 



38 Atkinson, Geo. F., "The Development of Agaricus arvensis and A. 

 comtulus," Am. Jour. Bot., i, 3-22, pis. i, 2, 1914. " Homology of the 

 Universal Veil in Agaricus," Myc. Centralb., 5, 13-19, pls. 1-3, 1914- 



