Hazen: Lire History or SPHAERELLA LACUSTRIS 227 
demonstrating the cellulose charectzr of the cell-wa'l, particularly 
in the case of the motile cells. The test is not always convincing, 
but by using rather strong sulphuric acid followed after a few 
minutes with dilute iodin according to Cohn’s directions, I have 
obtained a blue color which could leave no doubt in one’s mind. 
Although the test is less satisfactory with the resting-cells, prob- 
ably because they are somewhat coated witha gelatinous substance, 
yet even here the cellulose reaction is unmistakable. 
The sheaths which surround the bases of the cilia (Figs. 15, 16) 
usually disappear in the distortion produced by the action of sul- 
phuric acid, but there can be little doubt of the truth of the state- 
ment by Kerner* that they consist of cellulose, for they do not 
take up protoplasmic stains. 
THE RADIAL STRANDS OF PROTOPLASM 
The use of iodin or other proper stains demonstrates very 
clearly the protoplasmic character of the threads which radiate from 
the central colored mass. These threads often appear to end in a 
slight enlargement without coming into connection with the cellu- 
lose wall, but more careful examination often shows that they are 
finely branched at the end (Fig. 15) and probably these branches 
anastomose to form an exceedingly fine network close to the cell- 
wall. This structure is so delicate, however, that I have been un- 
able to demonstrate it by staining or plasmolysis. 
The protoplasmic strands are not always visible, even in mature 
zooids. Zacharias} intimates that zooids showing this structure 
are generally found in the stagnant water of old cultures, and sug- 
gests that they exhibit a strong approach to Amoeda-like organ- 
isms. I have found, however, that even young zooids in fresh 
cultures when kept in sunlight, show the threads well developed, 
so that it appears to be a condition accompanying vigorous assim- 
ilation and growth. 
THE CHROMATOPHORE AND PYRENOIDS 
Cohn ('50), considering the colored protoplasmic mass homolo- 
gous with the “ primordial utricle " of plant cells, applied to it the 
Mese are Natural History of Plants, 2: 630. 1895 
TO. harias. oe Untersuchungen iiber Pseudopodien-Bildung. 
Biol. Pits. 5: 261. 5. 
