508 Wager —The Nucleus of the Yeast-Plant. 
pointed out that ‘the method has resulted in demonstrat- 
ing the presence of masked phosphorus in the chromatin of 
all animal and vegetable cells, in nucleoli . . . pyrenoids 
of Protophyta, &c. ... It also shows that in non-nucleated 
organisms like the Cyanophyceae and Saccharomyces , the 
phosphorus-holding substance, or nucleo-proteid, although 
sometimes in the form of granules or spherules which have 
been taken for nuclei, is frequently dissolved in the 
cytoplasm.’ 
Errera (’ 98 ) states that he has been led to the following 
conclusions by a study of the cells of Saccharomyces Cere - 
visiae , part of which merely confirm former researches : — 
1. A relatively large nuclear body exists in each adult cell. 
2. Young cells contain no such body; a little later the 
old nuclear body divides, and one of its two daughters wanders 
through the narrow connecting-channel into the young cell. 
3. After the division is complete, the two cells are still 
kept together by a mucilaginous neck-shaped pedicel, which 
appears not to have been noticed hitherto. 
4. Carbohydrates are stored up in Yeast in the form of 
glycogen, which accumulates or disappears from the vacuoles 
very rapidly, according to conditions of nutrition and growth. 
The evidence in favour of a nucleus in the Yeast-cell, as 
shown by these investigations, is very considerable, but it is 
very evident that its exact nature has not yet been determined. 
This is due, partly to its small size, partly, as we shall see 
later, to the difficulty of interpreting various structures which 
occur in the cell, and partly to the fact that the nuclear 
apparatus differs materially in structure from the nucleus 
of the higher plants. 
Methods. 
Fixing and hardening. 
Various methods of fixing and hardening have been tried, 
including the chrom-osmium-acetic mixture ; chromic acid ; 
solution of picric acid in absolute alcohol ; picric and osmic 
