the Yeast Plant . 
75 
The nucleolus and the granular chromatin mass are all that remain 
of the original nucleus. Division now takes place by elongation of the 
nucleolus into an hour-glass shape with a long drawn-out middle portion, 
and the separation of the chromatin into two equal or nearly equal portions, 
as described and figured by Wager (' 98 , Figs. 61-78) and by Guilliermond 
(’ 98 , PI. Ill, Figs. 21-30). Guilliermond appears, however, to have mis¬ 
taken the chromatin granular mass for the nucleolus, and the nucleolus for 
the sporogenous cytoplasm. It is certainly not easy to differentiate the 
two, especially in the later stages. 
We are not now inclined to lay any stress upon the suggestion (Wager, 
3 98 ) that the chromatin granules are chromosomes. The whole process 
appears to be one of direct division or fragmentation, in which nothing in 
the nature of a spindle figure or definite chromosomes can be observed. 
At the same time, we must not forget that a nucleolar substance and a 
deeply stained chromatin granular mass take part in the process, which 
suggests that it may be of a rudimentary mitotic character, recalling that 
observed in Eiiglena (cf. Macallum, ' 99 ). ‘ The difficulty of observing all 
the details of the division is, however, so great that one must be very 
cautious in attempting an explanation of the facts observed.’ 
The disappearance of the nuclear vacuole and the formation of daughter- 
nuclei by division of the nucleolus appears not to be peculiar to the Yeast 
Plant. Some interesting observations of Ikeno (’ 03 ) upon the genus 
of simple Ascomycetes, Taphrina , show that comparable phenomena take 
place here. The ascogenous cell-nucleus produced by the fusion of two 
nuclei contains a nucleolus-like chromatin body. During the later stages 
of development the nuclear vacuole, which usually contains a network, 
undergoes disorganization, leaving the homogeneous nucleolus or chro¬ 
matin body free in the cytoplasm. The chromatin body then divides, 
either by a process of fragmentation or budding as in the T. Johansonii 
type, or by a rudimentary mitosis as in the T. Cerasi type, into the nuclei 
of the spores. The chromatin of the nuclear vacuole escapes into the 
cytoplasm either before or during disorganization. It is probably nutri¬ 
tive in character and serves for the growth of the cytoplasm of the 
ascus. He compares this breaking down of the nuclear vacuole to the 
disappearance of the nuclear vacuole of the Yeast Plant as described 
by Wager (’ 98 ). Whether the nucleolus lies inside, as in Taphrina , or out¬ 
side the nuclear vacuole, as in yeast, is quite irrelevant. What is important 
is that the vacuole has a temporary existence in both cases, and that it dis¬ 
appears entirely in both cases as a preliminary to the formation of the 
spores. May we not, therefore, regard the nuclear vacuole in both these 
cases as simply a storehouse for the temporary accumulation, or perhaps 
elaboration, of a chromatin substance for the use of the cell ? 
Numerous cases are known in which nuclear substance is extruded into 
