162 LEVINE: CyTOLOGY OF HYMENOMYCETES 
any part of the carpophore, particularly the pileus, and notes three 
different kinds of cells covered by a watery exudation. The 
well-known occurrence of water drops on mycelial cultures is 
another fact strongly against the conception of special water- 
excreting organs in the fungi. As I have pointed out, cytological 
study of the mycelial cells shows no specially differentiated organs 
for the excretion of water. 
The mechanical function ascribed to the cystidia by Buller 
for the Coprini is entirely out of the question in the Boleti. The 
pores need no such aid to keep them open. I have noticed in 
many species numbers of spores embedded in the mucilaginous 
covering of the cystidia. It seems that in this case the cystidia 
rather interfere with the dispersal of the spores than assist in it. 
The question as to the method of origin of the binucleated 
cells and the stage at which they appear in the development of 
the carpophore is of interest not only with reference to its bearing 
on the problems of the morphology and phylogeny of the Basidio- 
mycetes but also and even more in its bearing on the whole question 
of the nature of sexual reproduction. If a sporophyte with cells 
containing 2” chromosomes can arise by the simple omission of a 
cell division in a binucleated cell and if this process can occur at 
various points in a mycelium either simultaneously or over quite 
a period of development the fact is of prime significance in the 
interpretation of gametic unions of the more typical sort. As 
noted above, the absence of differentiated sex organs at the initi- 
ation of the carpophore must be taken as an established fact, but 
the possibility perhaps still remains that the binucleated cells have 
their origin by the migration of nuclei through clamp connections 
or hyphal anastomoses. Meyer (1896, 1902) and R. Hartig 
(1885) have argued on general grounds that such cytoplasmic 
fusions may have some sexual significance. The observations of 
Lutman (1910) and Rawitscher (1912) that in the smuts the 
nuclei do migrate through such connecting tubes are certainly 
suggestive. 
_ Voss’ (1902) claim that clamp connections are present in the 
rusts, if confirmed, must be certainly regarded as good evidence ; 
against their function as conjugation tubes, since sexual fusions 
of another type are present in the rusts. Voss’ observa 
