COPRINUS STERQUILINUS 213 



If we compare the basidia of Hymenomycetes generally, we are 

 safe in laying down the rule that the capacity of the four spores of 

 a basidium of any species is directly p>foportional to the capacity of 

 the basidium-body . But, other things being equal, the dimensions 

 (length, breadth, and thickness) of a cell vary with its capacity. 

 From this we may draw the conclusion that the dimensions of the 

 spores in Hymenomycetes are proportional to the dimensions of 

 the basidia which bear them, or, in other words, the size of the spore 

 and the size of the basidium in aiiy species are correlated with one 

 a7iother. 



One may ask : what causes the cytoplasm and the nuclei of 

 the basidium-body to pass upwards through the exceedingly narrow 

 sterigmatic channels into the spores ? It is now well-known, owing 

 to the investigations of cytologists : that the four nuclei of the 

 basidium-body are at first spherical ; that, as they pass through 

 the sterigmata, they become moulded by the pressure of the sterig- 

 matic walls into slender conical threads ; and that, as soon as they 

 have emerged into the spores, they at once resume their spherical 

 form. When, in a stained microtome section, one observes one 

 of these nuclei in a slenderly conical sterigmatic cavity, one may 

 feel inclined to think that, when living, it was creeping through 

 the sterigma in an amoeboid manner or that it was being drawn 

 through the sterigma by the contraction of a kinoplasmic thread 

 connecting the nuclear membrane with the apex of the spore ; ^ 

 but there is another possible hypothesis — first suggested to me by 

 Dr. Harold Wager — which appears to explain in a very simple and 

 satisfactory manner not merely the passage of the nuclei through 

 the sterigmata but also the passage of the cytoplasm. This hypo- 

 thesis is as follows. When the cytoplasm and the nuclei in a 

 basidium-body begin to pass upwards through the four sterigmata 

 into the spores, a vacuole, as we have seen, always forms at the 

 base of the basidium-body and then grows in size pari passu with 

 the emigration of the basidium-body's protoplasmic contents. 

 Moreover, the boundary surface between the vacuole and the 

 disappearing protoplasm is always curved in such a way as to 



^ Concerning the existence of the thread and its significance, vide vol. ii, 1922, 

 pp. 419-421. 



