yS Wager and Peniston.—Cytological Observations on 
deeply in nuclear stains, does the same, but at other times the reaction is 
very slight. We have obtained some evidence that the amount of phosphorus 
in the nucleus increases up to a certain stage and then diminishes again. 
During the height of fermentation, the granular mass around the nucleolus 
gives a strong reaction for it, but from the forty-eighth hour onwards it steadily 
decreases. 
The cytoplasm often contains bright refractive granules which are 
visible in the living cell. Some of these are composed of a fatty substance, 
others are similar to the metachromatin granules of Babes or the red 
granules of Blitschli, which are now called volutin granules. They vary 
very considerably in number at various stages. The volutin granules 
appear and disappear with remarkable ease, and are associated with active 
metabolic conditions. They occur either directly in the cytoplasm or in what 
may be called volutin vacuoles, and from one to three granules, possessing 
somewhat similar characteristics, are usually found in the nuclear vacuole. 
Glycogen is very abundant at certain stages. It is visible in the living 
cell in the form of clear bright refractive vacuoles or vacuolar spaces. 
It accumulates or disappears very rapidly according to the conditions 
of nutrition, and sometimes almost completely fills the cell. In healthy 
cells, the accumulation of a large quantity of glycogen seems to bring 
about a decrease in fermentative activity, which is only recovered as the 
glycogen gradually becomes used up again or disappears. 
In the process of bud formation, the nucleus divides amitotically 
into two equal or unequal portions, one of which passes into the daughter¬ 
cell together with a portion of the vacuole and chromatin. In spore 
formation, the nuclear vacuole and network disappear, the nucleolus becomes 
closely surrounded by chromatin granules and then divides by elongation 
and constriction into two equal or nearly equal daughter-nuclei, each 
of which consists of a portion of the nucleolus with its surrounding granular 
chromatin. These two nuclei again divide to form the spore nuclei around 
which the sporogenous cytoplasm accumulates. 
References to Literature. 
A full list of papers on the cytology of the yeast cell will be found in Wager (’ 98 ), Guillier- 
mond (’ 02 ), and Fuhrmann (’ 06 ). 
Babes (’ 89 ): Ueber isolirt-farbbare Antheile der Bakterien. Zeitsch. f. Hygiene, v, pp. 173-90. 
-(’ 95 ) : Beobachtungen iiber die metachromatischen Korperchen. Zeitsch. f. Hygiene. 
Barker (’ 01 ) : A Conjugating Yeast. Phil. Trans. Roy. Soc., cxciv, p. 467. 
- (’ 02 ) : On Spore-formation among the Saccharomycetes. Journ. Federated Institutes of 
Brewing, viii, p. 26. 
Butschli (’ 90 ): Ueber den Bau der Bakterien und verwandter Organismen. Leipzig, pp. 1-37. 
- (’ 96 ) : Weitere Ausfiihrungen iiber den Bau der Cyanophyceen und Bakterien. Leipzig, 
pp. 1-76. 
