288 RESEARCHES ON FUNGI 



accomplish it in Fig. 96 by removing the piece of hymenium on the 

 left of the Figure from B VIII to the bottom of D, and by replacing 

 it with the mirror-image of the remaining part of the hymenium 

 which stretches from B 6 upwards. To observe such a mirror- 

 image, it would only be necessary to place a mirror transversely 

 across the Figure with its base along the line B 6 to G 5 and facing 

 toward the top of the page. If a similar mirror-image were added 

 to the upper half of the hymenium on the right-hand side of the 

 Figure, we should have an arrangement showing a wave spreading 

 centrifugally, i.e. outwards from the centre, like a wave started 

 in the smooth water of a pond by a falling rain-drop. 



The elements of the hymenium in the section represented in 

 Fig. 96, can be separated everywhere into the same five classes 

 which we differentiated from one another in our surface-view 

 studies : (1) basidia of past generations, a a, which have discharged 

 their spores ; their ends are concave but look flat in the side view 

 here shown ; they are no longer protuberant ; (2) basidia of the 

 present generation, b b, which are easily recognised because they are 

 protuberant and bear spores ; (3) basidia of the coming generation, 

 c c, which are protuberant but do not bear spores ; they may or 

 may not have developed sterigmata as yet (vide, in the areas 

 B, C, and D the series of basidia opposite the Arabic numerals 

 4, 5, 6 ... 11 ; and on the opposite side of the Figure, in the 

 areas, H. G, F, and E, the basidia of the series 1, 2, 3 . . . 11, as 

 well as the basidium XI) ; (4) basidia of future generations, d d ; 

 these are non-protuberant and more or less pear-shaped ; they 

 will elongate and bear sterigmata and spores later on ; and (5) the 

 paraphyses, e e, sterile elements which never bear sterigmata and 

 spores ; at this stage of the development of the hymenium, they 

 are distinguished from the basidia of future generations by their 

 smaller size, their position between the lower parts of the basidia, 

 their vacuolated contents, and their tendency to become more or 

 less spherical as they enlarge. 



The most prominent elements of the hymenium in a cross- 

 section are the basidia of the present generation, for they alone 

 bear spores. It will be of interest here to state the relative ages 

 of these basidia as they are represented in the various areas of 



