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cestode tubercle, they differ markedly when microscopically examined, 
their perfectly defined outline contrasting strongly with the hazy de- 
marcation of the cestode tubercle. Their vascular origin is fairly well 
indicated by their position being always interlobular. The immense 
numbers that may be present may be judged from the fact that four 
are visible in a single field of Zeiss A, and that they seemed in this 
case fairly uniformly distributed through the organ. 
Two distinct layers are distinguishable in each tubercle: an 
outer or fibrous layer, which is, I believe, derived from the dilated 
coat of the vessel which carried the embryo to its destination, and a 
central portion which, to all appearance, is merely altered blood-clot. 
In some cases the boundary between the two layers is quite sharp 
and distinct; but generally, and more especially in the larger 
tubercles, the transition is less abrupt, the cellular central portion 
altering gradually into the distinctly fibrous outer layer. Generally 
at or near the centre, but occasionally a good deal excentric, will be 
found the nematode embryo, which has originated the whole of the 
changes described, and which bears so insignificant a proportion to 
the dimensions of the nodule in which it is contained, that it is 
easily missed unless the series of sections be quite complete. As a 
general rule, the embryo is coiled up into so close a knot, that no 
sign of it will be visible in more than one or two sections. The 
embryos themselves are in the earliest stage of extraoval life, and 
appear to possess no other organ than an empty intestinal canal ; 
and even this is so delicate that, after the action of hardening 
agents, little more remains visible than the cuticular layer of the 
worm. They are somewhere about three or four times the diameter 
of a red corpuscle in cross-section, and are proportionately rather 
short ; but owing to the way they are coiled up in the solid tissue of 
the hardened tubercle it is impossible to form more than a guess as 
to their absolute leDgth. Nor have I been able to make out any- 
thing definite as to the form of either extremity of the worms. In 
thin sections nothing, as a rule, can be made out, as even with 
careful fixative arrangements the little worm sections nearly always 
drop out, or, if retained by the fixative, show merely a structureless 
ring, from which nothing can be made out. On this account, 
tolerably thick sections are alone suitable for the study of the general 
relations of these nematodes. 
The tubercles, it is almost needless to say, far exceed the lumen 
of any interlobular vessel in diameter, so that if the above reading of 
their origin be correct, a considerable amount of proliferation and 
dilatation must have taken place. 
There is nothing, however, in the structure of the nodules that 
need negative the idea of their being derived from the occlusion of 
branches of the hepatic artery instead of from those of the portal 
system. 
The parentage of these embryos must for the present remain a 
