498 RESEARCHES ON FUNGI 



purely morphological nature. To its support, however, it is now 

 possible to bring a number of physiological facts which have only 

 recently been discovered. These concern the phenomena of spore- 

 discharge, and will now occupy our attention. 



In the Hymenomycetes it has already been shown that : 



(a) From the point of view of structure : 



(1) At the beginning of its development, a spore always forms 



a small projection called a hilum at the point where it 

 joins the sterigma and on one side of it (Vol. II, Figs. 2 

 and 4, pp. 7 and 12). 



(2) The axis of a spore taken through its point of attachment 



is always inclined to the axis of the sterigma (Vol. II, 

 Figs. 2 and 4). 



(b) From the point of view of function : 



(3) The four spores leave the basidium in succession.^ 



(4) The spores are violently shot into the air to a distance of 



about • 1-0 • 2 mm.2 



(5) Some 5-15 seconds before a spore is shot away, a small 



water-drop always begins to be formed at the hilum of 



the spore. ^ 



(6) As soon as the water-drop has attained a certain size, the 



spore is shot away along with the drop which clings to it.* 



(7) After discharge of a spore, the sterigma does not imme- 



diately collapse, nor does it bear a drop of water or other 

 substance at its summit.^ 



(8) The basidium-body does not collapse immediately as a result 



of the discharge of its spores. « 



All these statements, with slight differences in the measurements 

 given under (4) and (5), are true also for the Uredineae. 



The basidiospores of the Uredineae, as compared with those of 

 the Hymenomycetes, (1) are usually somewhat larger in size, and 

 (2) are usually shot to a somewhat greater distance from their 

 sterigmata (0-4-0 -85 mm. in the Uredineae, as compared with 

 0-2-0-65 mm. in the Tremellineae, and 0-*05-0-2 mm. in the 



1 These Researches, vol. i, 1909, pp. 133-147. ^ ibu,, p. 142. 



3 These Researches, vol. ii, 1922, pp. 8-17. Ibid 



^j,-j ^ Ibid., pp. 7, 272, 355, 417. 



Ibid. 



