STRUCTURE. 23 



dium, and hypertrophied basidium ; these are the three elements 

 which form the hymenium."* 



The only reproductive organs hitherto demonstrated in Agarics 

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

 I 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 very 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 endosgore being con- 

 stantly hyaline. It may he added here, 

 that in this order the spore is simple 

 and unicellular. In Lactarins and 

 Russula the trama, or inner substance, 

 is vesicular. True latex vessels occur 

 occasionally in Agaricus, though not 

 filled with milk as in Lactarius. 



Polyporei. — In this order the gill 

 plates are replaced by tubes or pores, 

 the interior of which is lined by the _ , , 



J biG. 4. — Polyporus gigantcvstra- 



hymenium ; indications of this struc- duced). 



tare having already been exhibited in some of the lower 



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

 vol. viii. p. 380. 



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

 found, in a certain stage, on the gills or lamellss. 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 Ifi/pomgcc?;, a genus of para- 

 sitic Sphceriaceous fungi. 



