of the Genus Hillhousia . 85 
Giemsa’s stain, and iron-haematoxylin (ferric alum and Heidenhain’s 
haematoxylin). 
In no case could any large deeply staining granules be detected, 
although very minute granules which stained rather more than the rest 
of the protoplasm were distributed throughout the reticulum. In dry- 
staining there was always an apparent concentration of the reticulum in the 
central part of the cell (Figs. 4 and 5 ), this being due to the flattening of the 
organism upon drying, and the consequent superposition of different parts 
of the reticulum. 
Wet-staining. The water containing the living organisms was placed 
in small tubes and centrifuged, after which the organisms were fixed in 
three parts absolute alcohol and one part glacial acetic acid. This removed 
both the calcium carbonate and the sulphur. The collection was then 
washed thoroughly in alcohol to remove the acetic acid, and afterwards 
stained with the same stains as used in the dry-staining method. In no 
case could any true chromatin be detected, but, as before, minute granules 
staining rather deeper than the rest of the protoplasm were distributed 
throughout the reticulum. Those granules at the angles of the meshes 
were a little more conspicuous than the others. 
No contraction of the reticulum was visible in any single instance 
(Fig. 6). We therefore regard the apparent concentration of stainable sub- 
stance, which is observed after staining subsequent to fixation by drying, as 
an artifact. 
The organism appears to be of a simple type in which as yet there is 
practically no differentiation of the protoplast. 
The granules in the network consist, as previously stated, 1 of a nucleo- 
protein, and if they are of the nature of a chromatin substance, it is one 
which differs considerably from the chromatin of more highly organized 
cells. It has little, if any, affinity for the usual nuclear stains. 
In the small species, Hillhousia palustris , the structure of the protoplast 
is precisely similar, but the meshes are fewer in number. (Compare Figs. 
6 and 10.) 
The Inclusions. The inclusions within the protoplast vary accord- 
ing to the amount of sulphuretted hydrogen and lime-salts present in the 
water. In a normal individual the cell is filled with refractive granules of 
variable size, which are of two distinct kinds. 
1. Globules of calcium carbonate. These are large globules varying 
from 6 ix to 10 /X in diameter. They are of a steel-grey colour, highly 
refringent, and lie in the meshes of the protoplasmic reticulum, one only in 
each mesh (Fig. 1). They are plastic, being able to pass through the cell- 
wall without rupturing it. When the organism has been killed by reagents, 
such as a concentrated aqueous solution of sulphuretted hydrogen, iodine in 
1 West and Griffiths, 1 . c., p. 403. 
