Massee. — On the Fungus Flora of New Zealand. 289 



adnate in the presence of an evident notch where the gill joins 

 the stem) ; free when the gills are completely rounded otf 

 behind, so that they do not reach the stem (Plate XXII., 

 fig. 11). Attention must be paid to the edge or margin of the 

 gill, as to whether it is entire, minutely toothed or serrated, 

 thin or acute, thickened or split. If a very thin section of a gill 

 is examined under the microscope it will present something of 

 the appearance shown in Plate XXIV., fig. 3, where a is the 

 trama, or central portion, which is a continuation of the hyphge 

 forming the flesh of the pileus ; branches of the hyphaB of the 

 trama give origin to the basidia (b), also to numerous other 

 bodies not bearing spores, and termed "paraphyses" (c). In 

 addition to these two structures, basidia and paraphyses, which 

 are always present in the hymenium, certain other bodies, of 

 larger size and projecting above the basidia, are present in 

 certain species, and are called " cystidia " (d). 



The special points connected with the stem are position — 

 as to whether central or excentric, solid or hollow, presence or 

 absence of ring or volva, fibrous or cartilaginous and polished 

 externally. Finally, the following features should be noted 

 as essentials in the discrimination of species : Dry or viscid, 

 smooth, scaly, or fibrous texture of pileus or stem ; presence 

 or absence of smell or taste, the latter, when present, some- 

 times very pleasant, at others intensely pungent, especially in 

 the genus Lactariicn, which is characterized by the presence 

 of latex, or milk, which escapes from the broken tissues as a 

 thick, white, or variously coloured liquid, in many instances 

 of a very pungent nature, so that a minute portion on the 

 tongue causes a burning sensation, which lasts for some little 

 time. 



In the general evolution of the Agaricinece the species 

 with decurrent gills are the lowest and most ancient type ; 

 next come species with adnate gills, followed by those having 

 adnexed gills ; while, finally, the species with free gills are 

 last to appear in the scheme of development, and are most 

 perfectly adapted for surviving in the general struggle, as 

 proved by superiority in numbers and wide geographical 

 range. In addition to the above structural sequence of de- 

 velopment, the Agaricinece further evolved a sequence of five 

 groups dependmg on the colour of the spores. The oldest in 

 time, and structurally the most primitive, have black spores ; 

 next follows a series with purple-brown spores, followed by a 

 third series having rust-coloured or ochraceous spores ; the 

 fourth series has salmon-coloured or pmk spores, while the 

 last and newest in order of time has white spores. In each of 

 these spore-colour groups the original sequence of the position 

 of gills is repeated — that is, we have genera with free gills, for 

 instance, in each of the colour-groups, and so on. The signi- 

 19 



