224 RESEARCHES ON FUNGI 



G. comatus, requires a proportionally increased amount of room 

 for its development. 



The Mode of Fall and the Adhesiveness of the Spores considered 

 in relation with Herbivorous Animals.— The observations recorded 

 in this Section were made by Mr. W. F. Hanna and the author 

 working conjointly. 



A spore of Coprmus sterquilinus, when shot away from its 

 basidium, is fully turgid and has the appearance shown in Figs. 92 

 (p. 219), 93 (p. 220), and 95, A, B. As the spore falls through the 

 air, the drop of water which was excreted at its hilum and which 

 it carries ujjon its exterior soon evaporates and disappears (Fig. 95, 

 C, D), and the spore, as a whole, takes up the position shown in 

 Fig. 95, C, D, i.e. one in which the flatter side is uppermost and 

 the more rounded side lowermost. This position may be considered 

 one of stable equilibrium to which the spore must return if, after 

 being disturbed therefrom, it is free to move. 



If a spore, after being liberated, while it is still fully turgid, 

 and before it has begun to shrink owing to loss of water, happens 

 to fall on to a glass slide placed beneath the pileus or on to a blade 

 of grass in a field, it usually comes to rest upon its more sharply 

 rounded side (Fig. 95, E). Then, as the spore dries up (a process 

 which may not take more than a few seconds), its upper flatter 

 surface becomes depressed, and very rapidly the whole spore 

 assumes a boat-shaped form (Fig. 95, F).! 



Evidence which seems sufflcient to prove that the spores of 

 Coprinus sterquilinus do settle and dry up in the manner just 

 described is readily obtained. One places a slide for two or three 

 minutes close under a pileus which is shedding spores under a 

 small befl-jar, obtains a thin spore-deposit, and then examines the 

 deposit dry in face and side views under the microscope. (1) If, 

 using a top light, one looks down on one of the dry spores from above 

 (c/. Fig. 94), one perceives that the spore has an oval outline and is 

 bilaterally symmetrical, that the spore-hilum is projecting upwards 



1 During the development of a spore, the flatter side of the spore is directed to- 

 ward the basidium-axis and the more rounded side away from this axis (c/. Fig. 95, A, 

 p. 227). When a spore dries up and becomes boat-shaped, it is always the flatter 

 side of the spore which bulges inwards, and never the more rounded side ; and this 

 is what we should expect on physical grounds. 



