STRUCTURE. 23 



dium, and hypertrophied basidium ; these are the three elements 

 which form the hymenium."* 



The only reproductive organs hitherto demonstrated in Agarics 

 are the spores, or, as sometimes called, from their method of 

 production, basidiospores.\ These are at first colourless, but 

 afterwards acquire the colour peculiar to the species. In size 

 'and form they are, within certain limits, exceedingly variable, 

 although form and size are tolerably constant in the same 

 species. At first all are globose; as they mature, the majority are 

 ovoid or elliptic ; some are fusiform, with regularly attenuated 

 extremities. In Hygrophorus they are rather irregular, reniform, 

 or compressed in the middle. Sometimes the external surface is 

 rough with more or less projecting warts. Some mycologists 

 are of opinion that the covering of the spore is double, consist- 

 ing of an exospore and an endospore, the latter being veiy fine 

 and delicate. In other orders the double coating of the spore 

 has been demonstrated. When the spore is coloured, the exter- 

 nal membrane alone appears to pos- 

 sess colour, the endospore being con- 

 stantly hyaline. It may be added here, 

 that in this order the spore is simpls 

 and unicellular. In Lactarius and 

 Russula the trama, or inner substance, 

 is vesicular. True latex vessels occur 

 occasionally in Agaricus, though not 

 filled with milk as in Laatarius. 



POLYPOREI. In this order the gill 

 plates are replaced by tubes or pores, C) x 

 the interior of which is lined bv the , 



. ... . *- * Polyporus gryantms ( re- 



hymemum ; indications of this struc- duced). 



ture having already been exhibited in some of the lower 



* Cooke, M. C., "Anatomy of a Mushroom, "in "Popular Science Review," 

 vol. viii. p. 380. 



t An attempt was made to show that, in Agaricus melleus, distinct asci were 

 found, in a certain stage, on the gills or lamellae. We have in vain examined the 

 gills in various conditions, and could never detect anything of the kind. It is 

 probable that the asci belonged to some species of Ifypomyccs, a genus of para- 

 sitic Sphoeriaceous fungi. 



