294 RESEARCHES ON FUNGI 



hymenium before it has produced any spores at all. A description 

 of the very young hymenium has been deferred until now because 

 the author's investigations began with the older states of the 

 hymenium, and because one can only understand the nature and 

 arrangement of the elements of the very young hymenium in the 

 light of the knowledge gained by a study of the older hymenium 

 which is producing and discharging spores. 



We shall consider the structure of the very young hymenium 

 which has not yet produced any spores, in surface view first. A 

 young gill was taken from a living fruit-body, placed flat on a 

 slide, and covered with a cover -glass without the addition of any 

 mounting fluid. The appearance of its hymenium is shown in 

 Fig. 100 at A. One observes a large number of more or less 

 prominent elements of various sizes projecting toward the eye. 

 These elements are all basidia. The largest ones, indicated by the 

 letter a, are the basidia of the first generation, i.e. those which will 

 produce and liberate spores first. In the piece of hymenium under 

 consideration, they had already attained their maximum diameter 

 and their maximum protuberancy ; while, in other areas of the 

 hymenium on the same gill, some of them had already developed 

 sterigmata or were in the act of doing so. 



Several first-generation basidia can be seen scattered about 

 over the area shown in Fig. 100, A. In this area can also be 

 seen basidia of medium size, one of which is indicated by the letter 

 6. These are the basidia of the second generation, i.e. basidia 

 which will produce and liberate spores, after the basidia of the 

 first generation, already referred to, have shed their spores and 

 collapsed. The other basidia on the area, indicated by the letter 

 c, are much smaller. They are evidently the basidia of the third, 

 fourth, and subsequent generations, which will develop and liberate 

 spores in the middle and last stages of the hymenial activity. The 

 paraphyses are deeply seated and more or less hidden between the 

 bases of the basidia, and no attempt has been made to indicate 

 their positions in Fig. 100, A. In order to observe the para- 

 physes, a gill was mounted under a cover-glass in water, and the 

 plane of focus of the microscope was lowered until the paraphyses 

 were reached. In Fig. 100, B, the positions of some of the 



