PSALLIOTA CAMPESTRIS 413 



their full size (D). A similar set of sketches, made in succession 

 with 10-minute intervals, is shown in Fig. 145. In this instance, 

 the spores of both the younger basidia attained to their full size 



A B C n 



oo oo 



FIG. 144. Psalliota campestris, wild form. Rate of growth of spores on 

 the ends of the sterigmata. A, the spores of two basidia, one set full- 

 grown and the other just coming into existence, as seen on a living 

 gill. B, C, and D, sketches of the same made successively with 

 intervals of 10 minutes. The spores attained full size in about 

 30 minutes. Magnification, 820. 



within 40 minutes. We may conclude, therefore, that the spores 

 of a Wild Mushroom at room temperatures take only from 30 to 

 40 minutes to grow to full size. 



In order to observe the course of the development of the spores 

 after they have attained full size, it was found necessary to resort 



A B C D E 



A 



FIG. 145. Psalliota campestris, wild form. Rate of growth of spores on the 

 ends of the sterigmata. A, the spores of four basidia, two sets full-grown 

 and two just coming into existence, as seen on a living gill. B, C, D, and 

 E, sketches of the same made successively at 10, 20, 30, and 40 minutes 

 respectively after the stage A. The young spores attained full size in a 

 little less than 40 minutes. Magnification, 296. 



to the compressor-cell method. A piece of a gill was taken from 

 a Cultivated Mushroom and placed on a very small water-drop in 

 a compressor cell. The lid of the cell was then closed down, so 

 that it just touched the gill at one spot. It thus became possible 

 to observe the hymenium with a magnification of about 300 

 diameters. By using this method it was observed that the 



