530 RESEARCHES ON FUNGI 



succeed this general discussion ; but the reader would do well at 

 the present moment to consult Fig. 216 (p. 537) which illustrates 

 a typical case of the orientation just described. 



Summarising the above discussion, we may say that the Hymeno- 

 mycetes arid the Uredineae present us with two different methods 

 for securing such an orientation of the basidiospores in space 

 as will permit of their being successfully discharged. In the 

 Hymenomycetes, the orientation consists of the following elements : 

 (1) the basidium is straight and has its axis perpendicular to the plane 

 of the hymenium ; (2) the sterigmata are terminal and have their 

 axes parallel to the axis of the basidium and therefore perpendicular 

 to the plane of the hymenium ; and (3) each spore has a terminal 

 position upon its sterigma. In the Uredineae, the orientation 

 consists of the following elements : (1) the basidium at first grows 

 with its axis more or less parallel to the axis of the teleutospore, 

 but subsequently becomes curved ; (2) the sterigmata are developed 

 on the convex outer side of the basidium ; and (3) each spore has a 

 terminal position on its sterigma. In consequence of these arrange- 

 ments the sterigmata become directed in the Hymenomycetes away 

 from the hymenium and in the Uredineae away from the teleuto- 

 spore-sorus. The same end — successful discharge of the basidio- 

 spores — is thus provided for both by the straight basidium of the 

 Hymenomycetes and by the curved basidium of the Uredineae. 



It is to be noticed that the straight form of the basidium with 

 the spores developed at one end is associated with the occurrence 

 of a compact hymenium, whilst the curved basidium with the spores 

 on the convex side of the curved end is associated with the isolation 

 of the basidia and their production from a teleutospore. That the 

 straight basidium, such as one sees in Agaricus, has a form best 

 suited for a basidium that is an element in a compact hymenium 

 seems obvious. In the Auricularieae where the basidia are septate, 

 and in the Coleosporiaceae where the teleutospores function directly 

 as basidia and become septate before the production of sterigmata, 

 we have a distinct hymenium in which the basidia are held together 

 by jelly. The basidia in both have straight axes : the sterigmata 

 become more or less parallel to the basidium-axis and the position 

 of the spores just before discharge is the same as in Agaricus, 



