656 DAVID HILT TENNENT. 
2. It represents a basement membrane, the true epidermis 
and cuticle having been thrown off. 
3. It is a true cuticle, i. e. the product of an epidermis. 
There have been some minor views, which may readily be 
referred to one or the other of these classes. 
According to the originators and supporters of the third 
explanation (Blochmann, 48, 1897) (Kowalevski, 44, 1895), 
and most of the recent workers, the epidermis is represented 
by deeply lying gland-cells, whose ducts traverse the muscle 
layers and the basement membrane and pour their secretion 
upon the surface of the latter. 
While the form which I have studied is small and perhaps 
would not be chosen for an investigation of the cuticle, it has 
served most admirably for the purpose. 
The large cells (giant cells) visible through the integument 
in living specimens claimed my attention early, and from 
their appearance gave the impression of being gland-cells. 
his was especially true of two lying in the anterior end, one 
on each side of the cystogenous organ, whose ducts were 
visible. 
These cells are from 0:02 mm. to 0°025 mm. long and from 
‘01 mm. to ‘015 mm. broad. In sectioned material they are 
seen to have finely granular cytoplasm, a prominent nucleus, 
and deeply-staining nucleoli. In some instances a duct 
passing outward to the sub-cuticular layer may be seen; in 
other examples the cells lie closely applied to the muscle- 
layers. 
For a time I was at a loss as to whether these were to be 
considered as gland-cells or whether they were myoblasts, 
such as are described by Bettendorf (45, 1897). 
A study of the embryonic stages convinced me that they 
were gland-cells. In the young stages of the cercaria they 
make their appearance after the appearance of the muscle- 
fibrils and before the formation of the cuticle. 
An interesting staining reaction served to convince me 
still further that these are glands which give rise to the 
cuticle. In aseries of sections which were overstained with 
