THE NUMBER OF SPORES 83 



each basidium bears four spores, it was calculated that the number 

 of spores on 1 sq. mm. was 13,600. 



The fruit-body used for this investigation was a large one (c/. 

 Plate I., Fig. 1). The pileus was 12 cm. high and possessed 214 

 gills. Each gill had an area of hymenial surface on its two sides 

 of 1800 mm. A simple calculation, therefore, showed that each 

 gill had produced about 24,480,000 spores, and that the number of 

 spores for the whole fruit-body amounted to the enormous approxi- 

 mate total of 5,240,000,000. 1 The period of spore-discharge for 

 large fruit-bodies of Coprinus comatus was found, by making field 

 observations, to last about forty-eight hours. On the average, 

 therefore, the fruit-body investigated would have shed 100,000,000 

 spores each hour of spore-fall. 



In the Coprini it is very easy to count the basidia on the 

 gills, for adjacent basidia on any small part of a gill are practi- 

 cally in exactly the same state of development, and are set at 

 regular intervals among the paraphyses. For other Agaricineae, 

 e.g. Psalliota campestris, this method does not succeed owing to 

 the fact that adjacent basidia at any one time are in the most 

 diverse stages of development. 



Polyporus squamosus. — A fresh fruit-body, which had just 

 reached maturity, was removed from a tree and placed with its 

 spores downwards upon a piece of smooth brown paper. Upon 

 this, after falling down the hymenial tubes, the spores gradually 

 accumulated in small white heaps (Plate IV., Fig. 27). A square 

 centimetre of the paper, on which were twenty-six heaps of spores, 

 deposited from as many tubes, was then carefully cut out and 

 stirred up with 25 cc. of water. The number of spores in five 

 drops of the mixture was then counted with the Leitz-Wetzlar 

 apparatus and, from the data thus obtained, it was calculated that 

 the number of spores which had been deposited on the square 

 centimetre of paper was 44,450,000. On the average, then, each 

 of the twenty-six tubes had produced 1,700,000 spores. 



As a control to the above calculation, an estimate was made 



1 The average length of the spores in one fruit-body was found to be 12*55 /i. 

 Placed end to end, therefore, they would stretch through a distance of forty-one 

 miles ! 



