MICROSCOPIC CHARAC1 1 RS 



IIO- 



lllis 



rather close together in an li\ menifoi in arrangement — an ixotric 

 dermial palisade, as in //. subsalmonius I Fig. { > and //. atnygdali 

 (Fig. 9), and (2) one in which the hyphae may be more or less ere* I 



hut not in a palisade, a simple i\ot riclioderiniuin | sec //. fuligineUS, 



Fig. 9; //. paludosus, Fig. l ). II. flavodiscus, Fig, LO; and others 

 Such a Layer may van from 20 /- to 500 /> in darkness, according to 

 the species. 



Type 6. The epithelium ( Fig. Id. b,c): The Feature <>! this layer 



is that it appears pseudoparenchymatous it one focuses down on the 

 pilens with a sufficiently high magnifying system. There are two 



types, based on the manner of origin of the component cells. In one 

 the radial surface hyphae become divided into short cells by the fur 

 mation of numerous septa, and the individual cells finally assume a 

 vesiculose shape and are approximately isodiametric. 



The second type consists of a palisade of cla\ ate-pedicellate cells 

 arranged perpendicularly to the cap surface and so crowded as to be 

 misshapen from mutual pressure in their enlarged part. This is tin- 

 type on which Heim (1957) established the genus HodophUus, based 

 on H. foetens (Fig. 10, c) and //. atropunctus. UnfortunateK the name 

 is not valid since no Latin description accompanied its publication. 

 We regard this type of epicutis to have been derived by a shortening 

 of the hyphae of a simple trichodermium, as previousl) stated. It is the 

 character on which Singer (1958) based the genus Hygrotrama, which 

 we are here recognizing as a section. 



The hypodermium is a differentiated layer beneath the epicutis but 

 is generally regarded as part of the cutis in contrast to the context. It 

 is not present in many agarics. It is rare in section Hygrocybe and 

 CamaropliijUopsis but present in some species of section Hygrophorus. 

 It usually consists of a highly colored layer, the hyphae often having 

 incrusted material on their walls, or the cells being enlarged differ- 

 ently than those of the context. A well-defined hypodermium has been 

 observed in H. amygdalinits (Fig. 9), H. fuligineus ( Fig. 9), //. paltt- 

 dosus, H. glutinosus, H. baker ensis, H. recurvatus, 11. colemannianus, 

 and others. In Hygrophorus it is apparently found only in species with 

 viscid to slimy pilei. More rarely a false hypodermium is found. In 

 H. fuscoalbus and in H. elegantulus there is a lower /one of somewhat 

 brownish hyphae, but they are neither parallel nor compact as in a 

 true hypodermium. 



Clamp Connections 



In our studies we have, in recent years, paid close attention to the 

 presence or absence of clamp connections on the h) phae of the Fruiting 



