228 RESEARCHES ON FUNGI 



the air in the box was very dry, there can be no doubt that the 

 spores must have lost most of their water and have become boat- 

 shaped during their fall and, finally, must have settled on the glass 

 slide hollow upwards and rounded keel downwards. 



Another way of proving that a boat-shaped spore, whilst falling, 

 has its hollow directed upwards and its rounded keel downwards 

 is as follows. A model of a boat-shaped spore, 1-2 inches long, 

 made of Japanese tissue paper, is liberated with its hollow down- 

 wards at a height of ten feet from the ground. One then observes 

 that immediately after liberation the model turns over so that 



its hollow comes to 



look upwards and its 



^ ^^^ Jfl^^ rounded keel down- 



^B ^^ ^^^ wards. In the end 



^JB ^^^ the keel alone strikes 



the ground. 



Normally, every 



Fig. 96. — Coprinus sterquilinus. An abnormal +u- i i •+ 



spore-deposit collected upon a glass slide set tUni ary spore-aeposir 



a few inches beneath a pileus of a fruit-body q£ CoVfinuS stevoui- 



growing on horse dung in the laboratory. Seen _ 



dry from above. The spores are in pairs and UnuS, collected On a 



boat-shaped. In each pair the hollows of the ,. , , . , . 



spores face one another. For explanation see Sliae set One incn, SIX 



the text. Photographed dry for W. F. Hanna inches Or six feet 



and the author by A. E. Field. Magnification, ' 



600. beneath the pileus, 



seen with the microscope from above, has the appearance shown 

 in Fig. 94 (p. 225) : each boat-shaped spore has its hollow directed 

 toward the observer and its keel directed away.^ As a rare 

 abnormality (only once observed), one may obtain a dry spore- 

 deposit in which the boat-shaped spores occur not singly but in 

 pairs, and rest not on their keels but on their sides, the hollows of 

 each pair of spores facing one another (Fig. 96). This abnormahty 

 may be explained as follows. The water-drops excreted at the 

 spore-hila of two or more spores situated on the same basidium 

 became abnormally large, so that they touched one another and 

 fused together. For a while the common drop enclosed between 



1 This is also true for spore-deposits collected within a few inches of the pileus 

 of Coprinus niveus, C. stercorarius, C. curtus, C. lagopus, Panaeolus campanulatus, 

 and Stropharia semiglobata. 



