120 



INTRODUCTION TO THE STUDY OF FUNGI 



The term Basioliomycetes is a comparatively new one, and 

 includes the older Hymenomycetes and Gastromycetes, on account 

 of their agreement in the possession of basidia, although they 

 still remain distinct on account of other differences ; but 

 mainly because in the former the hymenium is always naked 

 and exposed, whereas in the latter it is enclosed within a 

 peridium during the early stage, and is only exposed by the 

 rupture of the peridium, when the spores are nearly or wholly 

 mature. It is easy, therefore, to distinguish at a glance the 



true Hymenomycetes from the puff- 

 ball family or the Gastromycetes, so 

 different are they in external features, 

 and only correlated by a minute 

 character which is not to be demon- 

 strated without the aid of a micro- 

 scope. As Fries was not expert in 

 the use of this instrument, and 

 seldom took into account features 

 which could not be observed with 

 a pocket lens, he appears not to 

 have suspected the presence of 

 basidia in the Gastromycetes, whilst 

 he possessed such a remarkable in- 

 tuition of the relationships of most 

 of the groups, that he placed these 

 two orders in juxtaposition. Montagne and Berkeley were the 

 first to indicate the structure of the hymenium in the puff- 

 balls, and demonstrate the presence of basidia. 1 



It will facilitate a comprehension of the terms employed in 

 this connection if we indicate the features of the hymenium 

 in Agaricus, in its old and broadest sense one of the genera 

 of the Hymenomycetes, which may be accepted as the type of 

 the rest. The various modifications of the hymenium in 

 the several families may be reserved for illustration when 

 the Hymenomycetes come under special notice. It may be 

 premised that in the Agarics the hymenium or spore- 

 bearing surface covers completely the thin membrane, which 

 is pleated and folded on the under side of the cap, and con- 

 1 Annals of Nat. Hist, iv. (1840), p. 155. 



Fig. 47. — Hymenial cells of A garic, 

 a, paraphyses ; b, basidia ; c, 

 cystidia. 



