in the Hymenomycetes. 491 
states, in a paper of considerable interest, that he has examined 
thirty-five species of Hymenomycetes and finds only a single 
nucleus in the young basidia. The cells of the hyphae, on the 
other hand, contain one or more nuclei. The largest nuclei 
were found in species of Boletus and Amanita. Sometimes 
the nucleus has a vesicular structure, the chromatin forming 
a peripheral layer on the wall of the nucleus ( Amanita , Boletus). 
A nucleolus is very rare [Amanita muscarius). If the nuclei 
are very small, they are very dense and refringent. In Tricho- 
loma virgatum , the nuclei of the young basidia are granular ; 
they appear to have a reticulate structure, but do not possess 
a nucleolus. In species of Amanita (A. vaginata and A. por- 
phyria) the nucleus resembles a vesicle with a firm wall, 
thickened on the inferior side or on two opposite sides. But 
this appearance of the wall is due to the chromatin which is 
disposed on the periphery of the nucleus, against the wall of 
the nuclear sac, which can be distinguished sometimes when 
the nucleus is a little contracted. This nucleus always contains 
a nucleolus, sometimes free in the centre of nucleus, sometimes 
in contact with the periphery. When the nucleolus is free it 
seems to indicate that the cavity of the nucleus is not a vacuole, 
but that it contains a non-colourable substance, the nucleo- 
hyaloplasm of Strasburger. Rosenvinge was not able to 
make out any of the details of division. Indications of indirect 
division of the nucleus were found in Tricholoma virgatum , but 
he was not able to follow it out. The nucleus of the basi- 
dium divides first of all into two, then into four, or eight. 
In Amanita the sterigmata commence to form after the secon- 
dary division of the nuclei into four ; in Tricholoma after the 
first, but before the second nuclear division is accomplished. 
The nuclei pass from the basidia into the spores, each one 
of which receives one or two. In passing, if the nucleus is 
larger than the diameter of the sterigma, it accommodates its 
form to the latter and becomes elongated. 
No further observations were made upon this subject, so far as 
I know, until the year 1 891, when I communicated to Section D 
of the British Association a preliminary account of my observa- 
