3 i2 RESEARCHES ON FUNGI 



to the discharge, of the spores of subsequent generations : but, 

 owing to the fact that maturing basidia become protuberant 

 and develop their sterigmata before they develop their spores, 

 this danger is reduced to a minimum. With the horizontal micro- 

 scope, when watching the coming into existence and disappearance 

 of successive generations of basidia, I several times saw that a 

 maturing basidium, during its development, pushed aside one or 

 more of the waste spores which had overlain it or had been in 

 contact with it. The result was that the sterigmata were reared 

 above the hymenium in a free space, and that the new spores 

 were developed free from all obstacles. The practical advantage 

 of protuberancy thus became a matter of observation. Even when 

 a hymenium is thickly strewn with wasted spores, a considerable 

 number of basidia succeed in pushing up between the obstacles in 

 their way and in raising the tips of their sterigmata into freedom 

 in preparation for spore-development. 



Significance of the Collapse of Exhausted Basidia. It has 

 been pointed out that, some fifteen to thirty minutes after a 

 basidium has shed its four spores, the basidium-body contracts 

 in length so that it ceases to be protuberant (cf. Fig. 93, A, p. 272, 

 and Fig. 98, A and B, p. 292), and that at the same time the 

 sterigmata become drawn into the concavity which is formed 

 at the basidium-body end. It might be argued that the rapid 

 collapse of a basidium which has shed its spores is simply due to 

 the fact that the basidium is exhausted. In support of this one 

 might urge that the protoplasm in a basidium which has shed 

 its spores is devoid of nuclei and extremely small in amount, 

 and also that, since such a basidium has no further function to 

 perform, its death might well be expected to take place just when 

 it actually does. However, while all this may be true, yet it is 

 conceivable that a basidium should remain living long after it 

 has discharged its spores. Masses of cytoplasm separated from 

 all nuclear influence, as we know from actual experiments with 

 Amoebae and the cells of the Higher Plants, do not necessarily 

 die immediately after their isolation. If it were for the advantage 

 of the hymenium that basidia which have shed their spores should 

 remain protuberant and turgid, it seems to me very likely from 



