1898-99. | ON THE CYTOLOGY OF NON-NUCLEATED ORGANISMS, 489 
With regard to iodine solutions more particularly, it is necessary to 
use aword of caution. The prolonged action which is required with this 
reagent affects the proteids of the cell, and must change consequently 
the reactions of the cellular structures to staining solutions. I have 
found that it alters and changes the staining capacity of the cell in Spzvo- 
gyra, as well as of various animal tissues, and it can scarcely be admit- 
ted that it has no effect on the cytoplasm of the yeast cell. I find that 
it greatly diminishes the affinity of the chromatin distributed through- 
out the cell for hematoxylin and other dyes which, in the case of cor- 
rosive sublimate preparations, select only the chromatin. The reagent 
does, indeed, assist in fixing the yeast cells in such a way as to single 
out for special demonstration a spherical, more or less homogeneous 
body, known to certain investigators as the nucleus, and to others as the 
nucleolus or nuclear body ; but this property depends on the power of 
the iodine to change the chemical character of the cytoplasm in a 
greater degree than that of the nuclear body which is homogeneous 
and dense. ; 
Amongst the staining reagents which were used were hematoxylin, 
safranin, eosin, and acetic-methyl green and methylene-blue. The solu- 
tions of hematoxylin gave the best results and, more particularly, 
Delafield’s, Ehrlich’s, and Meyer's (hemalum). The solutions were made 
very dilute, so much so that it required always from sixteen to eighteen 
hours’ application of the fluid to bring out the full stain. The iron- 
alum hematoxylin of Heidenhain was also employed, and it is of value 
in revealing the structure of the cytoplasm of the yeast cell, but it is of 
no value as a micro-chemical reagent, and it does not show any sharp 
distinction between chromatin-holding and chromatin-free cytoplasm. 
Eosin was used as a counter stain to hematoxylin. Acetic-methy] 
green was employed on the fresh cells, and methylene-blue on the cover- 
glass preparations. 
The organic iron and phosphorus compounds were demonstrated in 
the manner described in the case of the Cyanophycee. The yeast cells 
were, for this purpose, always hardened in alcohol. To reveal the dis- 
tribution of organic iron the cells were mounted on a slide under a 
cover-glass, in a mixture of glycerine and fresh ammonium hydrogen 
sulphide, and the preparation kept at a temperature of 60°C. for a week. 
To demonstrate the organic phosphorus, the cells were kept in a solu- 
tion of ammonium molybdate in nitric acid for five hours, after which 
they were washed in distilled water for a few minutes, and then sub- 
jected to the action of a 2 per cent. solution of phenylhydrazin hydro- 
chloride, which converted the molybdic portion of the phospho-molyb- 
