W. Heape 
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nothing else than a concentrated layer of these connective tissue cells. 
That they are contractile is clearly shown, for, when the proglottis is 
contracted in length and swollen out dorso-ventrally, these cells are 
much elongated and are more crowded together (Fig. 2), while, on the 
other hand, when the proglottis is lengthened and flattened they are 
shortened and are not crowded together (Figs. 3 and 5). They no 
doubt serve the purpose of a protective layer, but they also serve as 
a means for extending the area over which any one of the dorso-ventral 
fibres exerts influence. One of these fibres, splitting up into two 
branches and then into four tendrils, is attached to four of these cells, 
whose superficial processes connect them with many points on the 
basement membi’ane and cause any contraction of that fibre to influence 
a considerable area of the surface of the body, a very important 
function. 
The network of connective tissue parenchyma and its connection 
with the superficial layer of cells is well shown in Fig. 2. The meshes 
of the network are wide, and the anastomosing protoplasmic processes 
which form it are very delicate and prolonged. It is interesting to 
observe that several of these cells, lying close below the superficial 
layer, have long processes projecting between the cells of the latter. 
Regarding the contractile fibres. There are four separate and 
independent systems which regulate the shape of the body or effect its 
movements, two distinct longitudinal, one circular and one dorso- 
ventral system. 
These contractile fibres have usually been designated muscular, but 
the evidence I have to offer will I think demonstrate this is certainly 
not the case for all and probably not the case for any of them in 
T. elliptica. 
In the specimens I obtained those preserved in osmic acid (Figs. 1, 
3, 4 and 5) were elongated and contracted dorso-ventrally. The 
longitudinal fibres were thus stretched, while the circular and dorso- 
ventral fibres were contracted. In Figs. 1, 3 and 4 all these fibres are 
well shown, the small bundles of superficial and large bundles of deeper 
lying longitudinal fibres are seen in section, while the dorso-ventral 
and circular muscles are seen contracted. In all cases the fibres are 
sharply marked and are distinctly different in density from the processes 
of the connective tissue cells of the parenchyma. 
On the other hand specimens preserved in corrosive sublimate and 
acetic acid (Fig. 2) were contracted longitudinally and distended dorso- 
ventrally. In these specimens the dorso-ventral and circular muscles are 
