NUMBER OF SPORES IN PUCCINIA GRAMINIS 549 



conditions for propagation and in a given time, such a fungus as 



Fig. 224. — Lycoperdon giganteum. A large white oval puff-ball, gathered August 4, 

 1915, from a field at Effingham, Surrey, England, just before the ripening of 

 the spores. Weight, 5 lbs. 3 oz. ; length, 13 inches; breadth, 11 inches; 

 height, 9-5 inches; circumference, 3 feet 3-5 inches. Held, at the request 

 of the author, by J. Ramsbottom. Photographed at the South Kensington 

 Natural History Museum. 



Puccinia graminis would achieve a greater increase in its numbers 

 than even the Giant Puff-ball. 



