268 



RESEARCHES ON FUNGI 



who fixed the tip of a cotyledon of a grass seedling (Setaria, 

 Sorghum, Phalaris) in a horizontal glass tube, while allowing the 

 rest of the seedling to project horizontally into the air, with the 

 result that the root end of the plant was turned upwards into 

 the air instead of downwards toward the ground. 



The Structure of the Gills. — The gills are very thin but also 

 very broad. The breadth varies in different fruit-bodies with the 

 size of the pileus, the largest pilei having the broadest gills. Gills 

 which are 10, 12, or even 15 mm. across are not at all uncommon 

 (Fig. Ill, p. 265). In the largest fruit-body which I have seen the 

 gills actually attained a width of 24 mm. (Fig. 113). Few other 

 Hymenomycetes, if any, possess gills of such great width as this. 

 A gill of Coprinus atramentarius, although very broad, is yet extra- 

 ordinarily thin ; for the thickness of a large gill, as measured 

 between the outer surface of the two layers of paraphyses, was found 

 to vary from 0-16 mm. near the pileus-flesh to 0-1 mm. near the 

 gill's free edge. Owing to its great breadth and extreme thinness, 

 an isolated gill of Coprinus atramentarius is far less rigid and far 

 more flexible than an isolated gill of an aequi-hymeniiferous fungus, 

 such as Lepiota procera or Psalliota campestris. 



The average breadth and thickness and the ratio of breadth to 

 thickness for the gills of large fruit-bodies of Coprinus atramentarius, 

 C. sterquilinus, and C cornatus are given in the following Table. 



The Breadth and Thickness of thz Gills of Large 

 Fruit-bodies of three Species of Coprinus. 



From the data given in the Table we may conclude (1) that the 

 gills of C. atramentarius are not only absolutely thinner than those 



afterwards turned round and round in circles for some days. This was due to the 

 sensitive tip of the cotyledon continuously sending stimuli to the motor region. 

 Whether or not the extreme apex of the stipe is able to behave in a similar manner 

 remains to be investigated. 



