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IVEY F. LEWIS AND CONWAY ZIRKLE 
daughter stalks. However, no case was found of more than two cells 
being borne on branches on a single stalk, which would indicate that the 
stalk does not persist through three generations. Indeed, if growth is 
inhibited, the stalks tend to blend into a common gelatinous sheath and 
appear as in figure 12. The stalks are elastic. It is quite a common 
instance for two sister cells to have stalks of different lengths, and in each 
instance observed the longer stalk was the thinner, as if it had been 
stretched out. Brand observed that the pressure of the cover glass would 
flatten out the jelly, which would resume its original shape if the presure 
were removed. 
Loffler's flagellum stain will show these stalks very well, a little better 
as a rule if pyrogallic acid be used in place of tannic acid. A good method 
of proceeding is to place a small amount of rapidly growing alga on a slide 
and allow it to dry until it has lost all of its water content. It should then 
be covered with the mordant and heated for ten minutes over a water bath. 
Much clearer results, however, have been obtained by allowing the alga 
to dry as described above and then fixing in the following solution: 
Sat. sol. anhydrous ferric bromide in ether i part 
Molar sol. pyrogallic acid in ether 2 parts 
The water in the gelatin will cause the solutes to ionize, and hence ink will 
be precipitated within the gelatin. This makes a good mordant for gentian 
violet and safranin. If the jelly has dried too much it can be impregnated 
with ink by having the fixing agent washed off with water. Another good 
fixing and staining agent for jelly is: 
Sat. sol. gentian violet in 95 % alcohol i part 
Formalin (40 % formaldehyde) I part 
This stains the jelly a dark red or purple and leaves the cell contents colorless. 
The chromatophore is typically star-shaped in the resting cell (figs. 
12, 13, 18). However, in the cells that are rapidly growing, the enlargement 
of the cell does not seem to be followed by an equal increase in the size of 
the chromatophore, so large vacuoles appear at its periphery. Its shape 
can then be best described as amoeboid. 
The chromatophore is of a dark red color, almost that of clotting blood. 
If, however, the plant is allowed to stand for a short while under water, the 
red coloring matter can be seen dissolved in the water and the gelatinous 
mass becomes grass-green. 
The centrally located body, which has almost uniformly been called a 
pyrenoid whenever it was observed, and will be considered such in this 
paper, is colorless in the living cell and appears only as a light spot in the 
chromatophore. Unstained it could very readily be mistaken for an arte- 
fact due to the refraction of light by the chromatophore. However, the 
"convergence of light rays" of Kufferath takes Heidenhain's haematoxylin 
very well and is not indifferent to gentian violet and safranin (figs. 2,9, 18, 
