308 RESEARCHES ON FUNGI 



when about to pass out from between the interlamellar spaces 

 into the open air at the base of the pileus, may be blown on to 

 the edges of the gills and stick there. In this way a certain number 

 of spores is often wasted. I have noticed this phenomenon in 

 connection with specimens not only of Panaeolus campanulatus, 

 but also of Anellaria separata and a number of other species growing 



: ? 



FIG. 104. Panaeolus campanulatus. Excessive excretion of water-drops and 

 the non-discharge of spores. A, four ripe spores of a basidium seen from 

 above ; B, the same excreting drops of water from their hila ; C, the drops 

 have attained full normal size (spores are usually shot away at this stage) ; 

 D, the drops have become supernormal and have stepped up on to the sides 

 of the spores ; E, the drops are still increasing in size and now almost touch ; 

 F, the drops have fused and the spores have been dragged together ; G, 

 excretion of water has continued and the spores in consequence have become 

 separated to the normal extent (cf. A) ; H, owing to a further excretion of 

 water the spores have been pushed more than the usual distance apart ; I, 

 excretion has ceased, the water has evaporated, and the spores have been 

 dragged together so that they adhere to one another ; J, the basidium has 

 collapsed and has dragged its four spores to the surface of the hymenium 

 to which they now adhere and from which they cannot escape. Magnifica- 

 tion, 660. 



in the open. The edges of the gills of Panaeoli sometimes become 

 quite black with the spores. 



Probably the chief cause of the accumulation of wasted spores 

 on gills is a failure in the discharging mechanism. The nature 

 of this mechanism has so far defied exact analysis. 1 However, 

 just before a spore is to be discharged, as was explained in Chapter I, 

 a drop of water is exuded at the neck of the sterigma (Fig. 104, 

 A, B, and C). When this drop has reached a certain definite size 

 (C), the spore is shot away from the sterigma and bears the drop 



1 For a discussion of this mechanism vide Chap. I, pp. 22-26. 



