THE NUMBER OF SPORES 87 



ever succeeds in producing a Mushroom plant capable of repro- 

 duction. 



Since a single large Coprinus coiiiatus fruit-body has been 

 shown to produce about 5,000,000,000 spores, and since the fruit- 

 bodies often occur in dense clusters together, and further, since 

 the mycelium in turf is possibly perennial, it seems probable that 

 successful spores do not number more than one in 20,000,000,000 

 in this case also. This may well be an under-estimate. For the 

 perennial Polyporus squamosus, which produces fruit-bodies from 

 the same tree, often year after year for several years, it has been 

 shown that in one case about 100,000,000,000 spores were produced 

 from the fruit-bodies of one plant in a single year. Since making 

 this calculation, I have found that large fruit-bodies of Polyporus 

 squamosus shed their spores continuously for a period of two or 

 three weeks. When collecting the spores on the brown paper 

 for the purpose of estimating their number, the fruit-body was 

 only allowed to remain in position for about two or three days, 

 for I then thought that spore-liberation would be at an end. 

 Hence it seems that I have rather under-estimated than over- 

 estimated the number of spores produced. Taking this into 

 consideration, and also the perennial character of the plants, 

 each of which may penetrate through a tree trunk and produce 

 clumps of fruit-bodies upon it in various places, it seems to 

 me that for every spore which succeeds in developing into a 

 mature plant producing reproductive bodies, something like 

 1,000,000,000,000 spores are wasted. How slight must be the 

 chances for any given spore of Polyporus squamosus finding a 

 suitable substratum for successful development ! 



Of thirteen kinds of fish investigated by F. W. Fulton,^ the 

 ling proved to be by far the most prolific in producing eggs. A 

 large specimen of this species, 61 inches long and weighing 54 lbs., 

 was found to possess a roe containing 28,361,000 eggs. Doubtless 

 this represented one year's output in spawn. Supposing that 

 the probable length of life of a spawn-producing ling is as much 

 as twenty years, the individual under discussion might altogether 



^ " The Comparative Fecundity of Sea Fishes," Ninth Ann. Rep. Fishery Board 

 for Scotland, 1890. Quoted from Cunningham's Marketable Marine Fishes, 1896. 



