the Yeast Plant. 
6 I 
only and of no morphological significance. They occur at all periods of 
fermentation, and badly nourished cells with these appearances are commonly 
met with in preparations of healthy yeast. 
The deeply stainable chromatin at the periphery of the nucleolus is 
well marked in some compressed yeasts, especially D.C.L. It is found 
in various positions on the surface of the nucleolus, thereby bringing about 
appearances strongly suggestive of nuclear structure. In one example 
of D.C.L. which we examined it was disposed in the form of a curiously 
regular network, which showed in sharp contrast to the faintly stained 
nucleolus beneath, presenting the characteristic appearance associated with 
typical reticulate nuclei (Fig. 65). 
The occurrence of chromatin or nuclein in this form on the surface 
of the nucleolus is not unique in our experience. It occurs in a 
similar position in Polyphagus Euglenae. We have also observed nucleoli 
in Closterium with varying amounts of chromatin on or at their surface 
(Fig. 100) ; and there are indications of a similar distribution of chromatin 
in the nucleoli of the root tips of Allium and Hyacinthus . 
There are some indications that a division of the chromatin precedes 
that of the nucleolus in budding yeast cells. Nucleoli are frequently met 
with possessing two distinct deeply stained hemispherical patches which 
in some cases lie close together (Fig. 78), in others farther apart (Figs. 79, 
94), and it is not uncommon to see an elongate nucleolus with one of these 
patches at each end (Figs. 55, 60, 77, 99). Further, in some cells we see 
two nucleoli each with a deeply stained patch (Fig. 80), and however small 
the portion of the nucleolus may be which enters the daughter-cell, it is 
invariably furnished with much the same amount of deeply stainable 
substance as the part retained in the mother-cell. 
Glycogen. 
Glycogen makes its first appearance in the cell in the early stages 
of fermentation in the form of minute refractive granules which give the 
characteristic reaction with iodine (Figs. 131-3). In the course of three 
or four hours these are replaced by larger masses of glycogen, which appear 
in the living cell as distinct vacuoles in the cytoplasm around the nuclear 
vacuole (Figs. 134, 135)- This explains the vacuolated appearance of the 
cytoplasm at this stage. At a later stage, these separate vacuoles disappear 
and the nuclear vacuole becomes surrounded by a single mass of glycogen 
(Figs. 136-40, 146). This gradually increases in size ; the nucleus becomes 
pushed to one side ; the nuclear vacuole seems to disappear, and finally the 
greater part of the cell space becomes occupied by glycogen (Errera, ’ 98 ; 
Wager, ’ 98 ). This is not visible in the living cell, owing to the high 
