1916] Yates: Histology of Californian Boletaceae 255 



solid, white within, 2.5 to 5 cm. long and 1.0 to 1.5 cm. thick. The 

 pileus in our Californian plants is 4 to 12 cm. in diameter. 



The Californian plants referred to R. granulatns agree very well 

 with the above description and come well within the limits of the 

 species as described above. The surface of the pileus in the plants of 

 this region varies in color from a light gray to a very dark brown, and 

 is always very viscid. 



Histology 



When examined under the microscope the surface of the pileus is 

 seen to be covered with long hairs. These hairs are about 4/£ in 

 diameter and 250 to 800|li in length. The walls are very gelatinous 

 and are embedded in a purplish jelly. In fresh material the hairs are 

 very hard to distinguish, since they are almost concealed by the jelly. 

 In dried material the hairs are brownish and are filled with certain 

 peculiar black dots which are probably similar to the black dots 

 formed by the drying of the liquid given off by the glands. The con- 

 text is made up of tangled hyaline hyphae, 2 to 3/i. in diameter. In 

 dried material black masses or dots are found in the context. These 

 masses are sometimes 10 to 12^ in diameter, irregular in shape and 

 appear to be of the same material as the black dots found in the hairs 

 (pi. 25. fig. 31). 



In the hymenium the basidia and paraphyses are found along with 

 certain peculiar cystidia or glandlike structures to be described below. 

 These glands are most abundant near the mouths of the tubes but also 

 occur some distance back of the mouths (pi. 25, fig. 28). 



The term "glands" is used for certain peculiar structures espe- 

 cially characteristic of species of Rostkovites. These structures re- 

 semble cystidia rather closely and have been so designated by Levine, 

 1913. Similar structures have also been observed in Ceriomyces com- 

 munis. Form B, on the stipe, as has been described. The glands appear 

 under the microscope as clusters or nests of large, swollen, hyphal 

 tips, dark in color and projecting some distance out into the tubes or 

 above the surface of the stipe. The individual cells are club-shaped, 

 30 to lOfx in length and 5 to 8/li in their shorter diameter. They pro- 

 ject 30 to 50/u, above the level of the hymenium, or above the surface 

 of the stipe as the case may be. Tlie glands occur in clusters of from 

 four or five up to several hundred. The larger clusters are 100 to 

 500/x, in diameter and appear as black dots or granulations at the 

 mouths of the tubes and on the stipe. The cells l)ranc'h from the 



