434 THOS. H. MONTGOMERY jr,, 
cytoplasm rarely appears to fill the whole cavity of the cell, on 
fixed material generally showing the arrangement of a coarse network 
of irregular strands, and is often limited (enclosing the nucleus) to 
one side of the cell cavity (Fig. 55, Pl. 40); probably this arrangement 
of the cytoplasm is an artifact due to the difficulty of the fixing re- 
agents passing through the dense intercellular substance (which may 
be equally well considered fused thick cell membranes) which is firm and 
elastic, binding the parenchym cells into a close complex so that on 
hand dissections long strips of it may be pulled off intact; the cells 
are thus closely united together, and in the adult stage are not 
separate lymphoid elements lying simply in close apposition. The 
only region of the body where it forms a less closely connected whole 
is in the plane of the oviducts (Fig. 75, Pl. 41), where its cells are 
arranged in a loose network, but even at this region none of them 
appear to be free-floating. Though, morphologically considered, it 
cannot be ranked as a tissue of lymphocytes, since it is a firmly con- 
nected whole, yet it is even in the adult not merely a supporting 
tissue, for the richness of the nuclei in chromatin and true nucleoli 
would show it to have some important part in the metabolism of the 
organisation. The following three main kinds of this tissue may be 
distinguished, though they intergrade into each other. 
1) The large-celled parenchym is especially characterized by 
‚the large size of its cellular spaces. It is found in the anterior trunk 
region (L. Par Figs. 13, 14, Pl. 37; Figs. 15—17, Pl. 38; Fig. 61, 
Pl. 40) where there are no body cavities, and extends backwards 
from that point as far posteriorly as the region of the mesenteries, 
from which point it is continued backwards as the perienteric mem- 
brane (to be considered in the next paragraph). In the anterior 
trunk region it completely envelopes the ovaries and the uteri; and 
anteriorly to the medio-ventral body cavity it completely invests the 
nerve cord also (Figs. 16, 17, Pl. 38). In the head it becomes 
greatly reduced in amount owing to the great development there of 
other organs and the heightening of the hypodermis; and at the 
anterior end of the head forms only a thin layer around the oeso- 
phagus. The other region of the body where this form of parenchym 
is well developed is in the tail lobes (Fig. 71, Pl. 41) and from there 
anteriorly (Figs. 72—74, Pl. 41) to the anterior region of the cloaca; 
here it completely fills the space between the body wall and the axial 
cloaca, its cells are radially grouped around the latter, and are largest 
next to the body wall. Anterior to this region (Fig. 75) it gradually 
