260 RESEARCHES ON FUNGI 



a new crop of spores. We are thus led to the supposition that, 

 in all probability, each area gives rise to a series of successive 

 generations of basidia. But a probability is a very different thing 

 from a fact established by direct observation. In order to test 

 the correctness of the deduction just brought forward, it seemed 

 highly desirable to do what I believe has never before been 

 attempted, namely, to watch the changes taking place in one and 

 the same piece of hymenium for several days. Accordingly, some 

 special investigations were undertaken which will now be described. 

 We may here anticipate their result by stating that the test of 

 direct observation has conclusively demonstrated the correctness 

 of the idea of a series of successive basidial generations. 



Apparatus and Method for Observing the Development of the 

 Hymenium. In devising the apparatus and method about to be 

 described, the object aimed at was to observe the changes taking 

 place in one small area of the hymenium under sufficiently normal 

 conditions of development and for as long a time as possible. 



A glass crystallising dish (Fig. 91, D), 5 inches in diameter 

 and 2 deep, was stood on its side so that it rested on a wooden 

 block (W) set on a stand (S) having a circular top. The dish 

 was held in place by a vertical elastic band (VB). The fruit- 

 body to be examined, together with the surface mycelium attached 

 to the base of the stipe and a little of the substratum, was then 

 removed from the culture dish, and with the aid of a sharp scalpel 

 two parallel and vertical cuts were made through the pileus on each 

 side of the stipe about one quarter of an inch apart. Two pieces 

 of the pileus were thus removed. From one of the gill-bearing 

 pieces of pileus still left attached to the stipe all the gills were 

 dissected away except one, which thus being freed from its fellows 

 afforded an admirable object for exact study. In general appear- 

 ance it resembled the right-hand gill shown in Fig. 87 (p. 251). 

 Immediately after being operated upon, the fruit-body was placed 

 inside the crystallising dish in its natural position as shown in the 

 accompanying Fig. 91, so that the gill to be examined (the one 

 to the right) had its median plane vertically situated. The base of 

 the stipe, together with the mycelium and horse dung attached to it, 

 was then surrounded with wet cotton-wool (CW) held in position 



