the Yeast Plant. 
55 
A very delicate differentiation is possible with a i per cent, aqueous 
solution of gentian violet, but it is difficult to manipulate owing to the 
rapidity with which it washes out in alcohol. It is necessary to stain from 
12-24 hours. 
Gram’s aniline violet is a useful stain for volutin. 
Hanstein’s aniline violet (safranin and acid-fuchsin) is a useful cyto- 
logical stain which has the advantage of acting rapidly (5-10 minutes). 
Jenner’s stain, made by dissolving Grubler’s water-soluble eosin, yellow 
shade, and Grubler’s medicinal methylene blue separately in methylic 
alcohol, and mixing them in the proportion of 125 c.c. of a 0-5 per cent, 
solution of eosin and 100 c.c. of a 0*5 per cent, solution of methylene blue, 
has also been used, and has given satisfactory and interesting preparations. 
The methods employed for the detection of organic phosphorus and 
masked iron are described in detail in the sections dealing with phosphorus 
and iron. 
The Nucleus. 
a. The Vacuole. 
The structure of the vacuole can be most easily observed in yeast 
which has been fermenting from 5-15 hours, fixed in iodine and stained 
in a 0-5 per cent, watery solution of haematoxylin after previously mor- 
daunting in a 2-5 per cent, solution of common alum. It contains, as was 
pointed out in 1898, a loose network consisting of a faintly stainable substance 
resembling linin with numerous deeply stained chromatin granules on the 
threads (Figs. 96-8 and 101-8). The threads of the network are peri¬ 
pherally disposed, lining the interior of the vacuole (Figs. 96, 102-5). 
V 
This is in agreement with Macallum’s statement that chromatin occurs 
at the periphery of the vacuole. The network is continuous with the plastin 
substance forming the basis of the nucleolus (Figs. 95, 102, 104, 105, 112), 
and the coarser threads and their connexion with the nucleolus can be 
clearly seen. The nucleolus and chromatin network bear the same morpho¬ 
logical relation to each other as in such typical nuclei as are found in 
Spirogyra , in the root tips of Allium and Phaseolus , and in the pollen 
mother-cells of L ilium , except that the nucleolus is attached laterally 
to the network (Figs. 102, 111, etc.), and is thus in direct contact with the 
cytoplasm. 1 
The large size of the nuclear vacuole (Figs, in PI. VI) is so dispro¬ 
portionate to the size of the cell, and contains such a large quantity of clear 
1 Janssens and Leblanc (’98) were the first to recognize that the prominent vacuole of the Yeast 
Plant is the nucleus. They unfortunately confused the real nucleolus with the moving granule 
inside the vacuole, which they regarded as the nucleolus. In a later paper Janssens (’03) em¬ 
phasizes this erroneous interpretation by stating that this central granule comes to lie laterally 
apparently on the outside of the nucleus, through the contraction of the nucleus on fixing and the 
retreat of the granule into one of the folds of the membrane. 
