J. Johnstone 
393 
PL V, figs. 3 and 4). I have no doubt that the appearance is that of an 
artifact produced by the action of the fixing reagent. 
Tlie cuticula rests on a layer which is usually called a basement 
membrane—but which appears to be only a specialised part of the 
underlying parenchyma. It stains pure blue with methyl-blue-eosin 
and is, as a rule, strongly contrasted with the adjacent layer of 
parenchyma, which stains with difficulty, and with the red staining 
integumentary museles. Sometimes the basement membrane is so faint 
as to be unrecognisable. 
The parenchyma. This tissue appears at first sight to consist of 
polyhedral cells which are closely apposed and possess walls which stain 
with difficulty, and cell bodies which do not stain at all, or only 
extremely faintly. It is usually so figured and it is so represented in 
PI. XXIII, figs. 19 and 21, but it is certain that it consists of a relatively 
coarse reticulum which can be stained with methyl-blue-eosin by 
dififerentiating so that the red of the stain disappears and only the blue 
is left. The reticulum bounds spaces which contain only fluid con¬ 
tents. It includes small nuclei but it is difficult to be sure that these 
have any constant situation with regard to the meshwork. Among the 
other elements of the parenchyma are round or ovoid cells with prominent 
nuclei and these cells are large in comparison with the intra-reticular 
spaces: they probably belong to the same category as that to which the 
subcuticular cells belong. The parenchyma is the ground tissue of 
the Cestode, and fills the interspaces between the other organs. It 
can be traced right up to the cuticle, being differentiated beneath the 
latter to form the basement membrane. 
The subcuticular cells. PI. XXIII, figs. 19 and 21. These are situated 
beneath the basement membrane and form a more or less continuous 
layer embedded in the parenchyma. They are never so numerous as to 
form a closely packed stratum, and there is little significant difference 
in their relative abundance in different parts of the body. They are 
about 8 ju in longest diameter and have round or ovoid cell bodies which 
are produced into delicate prolongations which can be traced towards 
the cuticle : usually the subcuticular cells are so arranged that their 
long axes are perpendicular to the surface of the body. The eells have 
large nuclei, prominent nucleoli and granular cell protoplasm. Among 
them are apparently isolated nuclei which probably belong to the 
pai’enchyma. 
The function usually ascribed to the subcuticular cells is that of the 
secretion of the cuticle. The latter appears to be a secretion from 
Parasitology iv 
26 
