BASIDIA AND THE DISCHARGE OF SPORES u 



faces in this direction also. For Psalliota campestris, the sequence 

 of events for a single basidium during spore-discharge is represented 

 semi-diagrammatically in Fig. 3. The hilum of the first spore to 

 be discharged (A) excretes a drop of water which quickly grows 

 to its maximum size (B and C). At this stage the spore is shot 

 away and, at the same moment, the water-drop disappears (D). 

 After a short interval of time, a few seconds or minutes, another 

 spore is shot away (E, F, G, and H) ; then, after another interval, 

 a third (I, J, K, and L) ; and finally a fourth (M, N, O, and P). 

 For each spore, as is shown in the Figure, discharge is preceded 

 by the excretion of a drop. A side view of a basidium, showing 

 stages in the discharge of the last two spores, is given in Fig. 4. 

 The interval between the moment when a water-drop first becomes 

 noticeable and the moment of spore-discharge was observed to be 

 about 5 seconds. 



Not infrequently, soon after a drop has begun to form at the 

 base of one spore, another drop begins to form at the base of a 

 second spore, and so on. Thus in some basidia one may see two, 

 three, or even four drops in course of growth at one time. The 

 almost simultaneous production of three such drops is shown in 

 Fig. 5. The relative ages of the drops are directly proportional 

 to their size. Thus, at C, the drop on spore No. 1 began to be 

 excreted before that on spore No. 2, and that on spore No. 2 before 

 that on spore No. 3. The sterigma which begins to produce its 

 drop first shoots off its spore first, and so forth. When the drops 

 on a basidium appear almost simultaneously, the four spores are 

 shot off their sterigmata in close succession. A basidium therefore 

 sheds its four spores, after spore-discharge has begun, much more 

 quickly when the sequence of events is as represented in Fig. 5 

 than when it is as represented in Fig. 3. 



The size of the drop excreted before spore-discharge is very 

 constant in the fruit-bodies of any one species, but in different 

 species it varies considerably. However, it bears a certain relation 

 to the size of the basidia and of the spores. The following Table 

 shows the relation between the size of the spores and that of the 

 drops in two species. The fourth column gives the number of 

 seconds taken for the growth of a drop before spore-discharge. 



