4 i2 RESEARCHES ON FUNGI 



correlated with the amount of nutrient protoplasm which each 

 kind of spore is to receive. This conclusion suggests another of a 

 more general kind, namely, that the fluctuating variations in the 

 size of the spores for any species belonging to the Hymenomycetes 

 are correlated with the amounts of protoplasm in the basidia 

 which produce the spores. Now the amounts of protoplasm in 

 the basidia usually vary directly as the volume of the basidia. 

 It therefore seems highly probable that, if of two individual fruit- 

 bodies of the same species one has spores which on the average 

 are larger than those of the other, the one with the larger spores 

 will have the larger basidia. Spore- size is not improbably correlated 

 with corresponding variations in size in all the elements of the 

 hymenium, and perhaps of all the elements of the whole fruit- 

 body. In studying a large number of species of the genus Coprinus, 

 I have found that the species with the largest spores have the 

 largest basidia, and those with the smallest spores the smallest 

 basidia. So far as species of Coprinus are concerned, there is 

 undoubtedly a strict correlation between spore-size and basidium- 

 size. 



Rate and Mode of Development of the Spores of an Individual 

 Basidium. The rate of development of the four spores of a single 

 basidium from their first rudiments up to full size was determined 

 by direct observations made upon a Wild Mushroom gathered in 

 England. A gill was dissected off the fruit-body and placed on 

 a glass slide, and over it was laid a large cover-glass. No mounting 

 fluid was employed ; but, on the autumn day when the investiga- 

 tion was undertaken, the air was almost saturated with moisture, 

 so that the gill under the cover-glass lost water but very slowly 

 indeed. Two basidia, one with fully pigmented nearly ripe spores 

 belonging to an older generation, and another which had developed 

 sterigmata but not spores and belonged to a younger generation, 

 were watched, and sketches of them were made at intervals. The 

 first beginnings of the new spores on the sterigmata of the younger 

 basidium are shown in Fig. 144 at A. After an interval of 10 

 minutes from the beginning of the observations, the spores had 

 grown to half their full diameter (B), after 20 minutes to about 

 three-quarters (C), and at the end of 30 minutes they had attained 



