1044 DR. F. E. BEDDARD ON 
little difficult to make out. But it is clear that it forms a tube, 
slightly sinuous, which is walled by a layer of cells in which 
appear to lie masses of secretion, which masses are colloid in 
appearance and deeply stained by hematoxylin. They are found 
also within the tube, especially in its more dilated regions. 
These masses of secretion, as I suppose them to be, are shown 
Text-figure 3. 
Monccocestus erethizontis. 
A. Cirrus-sac in longitudinal section. 
a. Its cellular sheath. ce. Slightly produced cirrus. 
B. Proximal end of vas deferens. 
ci. Cirrus-sac. 7. Longitudinal muscular fibres. v.s. Dilatation of 
vas deferens. 
in text-fig. 3. The tubular character of this dilated region of 
the vas deferens is very obvious in the younger proglottids, where 
the cells of the tube have not become modified by the secretion 
spoken of. In parts, for instance, in the terminal dilatation 
