4 8 Fraser . — Contributions to the Cytology of 
fusion takes place, and, since no evidence of the union of the two spiremes 
was obtained, it may be supposed that each continues its development 
separately, and separately breaks up into the reduced number of chromo- 
somes. There are sixteen chromosomes in the divisions in the ascogenous 
hyphae, and the sixteen which appear in the heterotype prophase are thus 
made up of two sets of bivalent chromosomes, eight of which have been 
derived from each spireme ; in the same way the definitive nucleus of the 
ascus is a double structure, representing two nuclei enclosed within one 
membrane. This view is further borne out by the occasional appearance 
of a nucleus in which the spireme, in the second contraction, is aggregated 
into two masses, or of an ascus containing two nuclei in synapsis, which 
have no doubt failed to fuse, but have nevertheless continued their 
development independently. 
The third mitosis has been regarded by Maire and Guillermond as 
vegetative, and Guillermond states that in H. rutilans the number of 
chromosomes in the third telophase, as in the first and second, is sixteen. 
If, however, the conclusions drawn from the present research be correct, 
the sixteen ends radiating from the pole at this stage represent, not sixteen 
rods, but eight V-shaped chromosomes. The postmeiotic number, that is 
to say, has become apparent, and the fusion in the ascus is compensated'. 
Nemec ( 35 ), experimenting with the root-apices of Phanerogams, found 
that treatment with 075 per cent, of chloral hydrate produced degeneration 
of the spindle fibres; cell division is thus inhibited, but the daughter nuclei 
separate and binucleate cells appear; in these the two nuclei either fuse, 
subsequent divisions showing double the somatic number of chromo- 
somes, or divide simultaneously; in the latter case three cells are formed, 
the middle one containing two nuclei ; these may fuse and show the double 
number of chromosomes in their divisions. 
After a few hours mitoses showing double the somatic number of 
chromosomes cannot be identified, reduction having apparently taken place. 
Nemec observed in Pisum a large cell, quite like those which contain two 
nuclei or a nucleus with the double number of chromosomes, containing 
a nucleus in the late anaphase, which showed the ordinary somatic number. 
This he regards as a reducing division. It seems quite possible that such 
divisions correspond to the third division in the ascus. This division 
resembles an ordinary vegetative mitosis, but shows in the metaphase the 
double number of chromosomes, and in the anaphase the ordinary number 
(half that shown in the metaphase). The relation of the two stages would 
not, however, be obvious, except where, as in the ascus, their connexion 
could be recognized in some other way. The process, compensating as it 
does a vegetative or asexual fusion, is much less elaborate than the meiotic 
reduction. 
Pividence of similar fusions and reductions in graft hybrids has 
