16 GENERAL CONSIDERATIONS 



common to all thin-walled hyaline basidiospores is the accumulation of 

 minute oil droplets ( or other refractive material ) against the inner sur- 

 face of the spore wall, and under high dry objectives such spores ap- 

 pear minutely punctate. 



Chemical reactions of the spore wall are often of significance in the 

 delimitation of taxa at all levels in the Hymenomycetes, but, as with 

 ornamentation, the spores of Hygrophorus offer little in this regard. 

 One species related to Camarophyllopsis and two related to Hygrocybe 

 have been found to give a positive amyloid reaction. KOH, which 

 causes a color change on spores in some groups, notably the Cortinaria- 

 ceae, has no effect in Hygrophorus. 



Basidia 



As already emphasized one of the important generic characters of 

 Hygrophorus is the long basidia. In instances of a questionable generic 

 identification, the final decision may rest on whether or not the basidia 

 are narrow and elongated. A typical Hygrophorus basidium is about 

 40-52(60) X 6-8 /a. In more than half of the species studied we found 

 the basidia to be uniformly 4-spored, and the sterigmata typically are 

 prominent. 



Throughout the genus however, according to the species, the size 

 of the basidium and the number of spores borne on it deviate from the 

 usual condition described above. In some species of section Camaro- 

 phyllopsis relatively small basidia are found. For example, in H. fallax, 

 H. angustifolius, H. basidiosus, H. deceptivus, and H. microsporus small 

 basidia 30-40 X 4.5-6.3 fi are the rule. Examples of exceptionally large 

 basidia are H. inocybiformis, 62-84 X 10-12 /x, and H. amygdalinus, 

 42-74 X 7-11 p. Additional examples could be cited. There appears to 

 be a general correlation between size of basidium and of spores in 

 Hygrophorus. In H. megasporus the spores measure 12-18 X 7-9 ti and 

 are borne on relatively large basidia, 55-71 X 7-11 tt. In H. monticola 

 the spores are 10-14 X 5.5-7.5 /*, and the basidia are 56-82 X 7-11 /x. In 

 several species related to H. peckianus the spores are about 4.5-6 X 

 3.5-4.7 fi, and the basidia are small. 



It is desirable at this point to refer again to the dimorphism of the 

 basidia in H. firmus var. firmus by Dennis (1953) and re-emphasize 

 the desirability for critical cytological work and studies on the sexuality 

 of fungi showing this phenomenon. 



The number of spores borne on each basidium may vary with the 

 species. In fact, variant-spored forms are common in Hygrophorus, as 

 they are in Mycena ( Smith, 1934 ) , comprising about forty percent of 

 the material we have studied. H. subcaespitosus was found to be con- 



