1916] Yates: Histology of Calif or nian Boletaccae 263 



lean toward such genera as Boletus, Boletellus, etc.. while the gymno- 

 carpous forms tend toward genera in which the annulus is wanting, as, 

 for example, the genus Kostkovites. In regard to the absence of the 

 veil in liostkovites I may state here that, while I have made no such 

 careful study as Zeller made of the young stages of C. Zelleri, I have 

 had an abundance of material in verj' young stages and have not 

 noticed the occurrence of a veil in any of this material. A veil rudi- 

 ment may, of course, be present, but there is nothing comparable to 

 the very marked veil found in individuals referred to Ceriomyces com- 

 munis and Ceriomyces crassus. 



Another fact which points toward the view that Ceriomyces is a 

 genus of relatively undifferentiated forms is the occurrence of struc- 

 tures resembling "glands" on the stipe of certain plants referred to 

 Ceriomyces communis. These "glands" attain their maximum de- 

 velopment in species of Rostkovites. It is true that the stipe in certain 

 other genera is described as glandular dotted, but, as has been previ- 

 ously explained, in the case of Boletus luteus, at least, the glandular 

 dots are very different in their origin and structure from those found 

 on the stipe of species of Rostkovites. 



Again, when we consider Suillellus, we find certain species, or at 

 least certain individuals, referred to Ceriomyces taking on something 

 of the distinguishing characters of Suillellus, that is. the red mouths 

 of the tubes. Ceriomyces auriflammeus has tubes with mouths which 

 are red at least in a certain sen.se. 



When we come to the third j^art of our problem, that of finding 

 histological characters to aid in the determination of fresh or more 

 especially of dried material, the results of this investigation must be 

 said to be inconclusive so far as general and extensive recognition is 

 concerned. For example, at the present stage of the investigation it 

 would he impossible to construct a generic key or a specific key to the 

 species, based upon histological characters alone. However. I do find 

 it possible to determine, by their histology, the different forms under 

 the species, both as to their identity and as to their separation from 

 other forms referred to the same species. AYhile at present I am not 

 able to bring forward hi.stological details to separate all the species, it 

 seems probable that this might be possible if the series of species de- 

 scribed as to their histology were sufficiently large. 



Finally, it may be well to state that the results of this study have 

 been to increase my own belief, at least, in the constancy of certain 



