22 
HEMOLYMPH NODES OF THE SHEEP 
zagged about, but small amounts of which were but seldom found in the 
peripheral or central — in the sense of internal — blood islands or blood 
spaces. (Fig. 2.) However, if the injection was a fairly complete one, 
the gelatine mass or the India ink was distributed quite uniformly 
throughout the node, and some of it was rarely found within the follicles ; 
although instead of penetrating these, it usually surrounded them. In 
some places, the masses of injected material formed an incomplete and 
a very irregular circuit, parallel and internal to the peripheral blood 
space, which was, however, always separated from the former by a very 
thin barrier of lymphatic tissue. In case of injections of India ink by 
puncture, the resulting picture was always similar to that obtained by 
injections from the vena cava; but since the puncture injections were 
generally much completer, a greater amount of injection material was 
present. In these instances some of it was found in the peripheral blood 
space (sinus), in some of the blood islands, and not infrequently in some 
of the follicles as well. These puncture injections, whether made direct- 
ly into a node or indirectly into an adjacent one, were, of course, also 
venous injections (figs. 5 and 6). Strangely enough, out of scores of 
nodes injected from the venous side, only a few showed the injection 
mass lying in large blood spaces in the center of the node. In two cases 
of injection by puncture, the India ink also found its way into an artery 
lying near a vein, wholly outside of a node. In the latter cases it seems 
likely that the ink entered the outlying artery through accidental punc- 
ture of one of its branches within the node, rather than by passing from 
the larger blood sinuses or lacunae into a capillary or an arteriole and 
then to the parent trunk. Unfortunately, however, the material at hand 
does not justify a definite conclusion regarding these rare accidental 
results. 
Carmine gelatine injections from the aorta gave very similar re- 
sults. (Fig. 7.) If the injection of the node was only a partial one, 
however — as was usually the case — the injected mass was found mainly 
in the venous lacunae at the periphery, and to a far less extent near the 
center of the node. Hence in the case of a complete injection it would 
be difficult indeed to distinguish an arterial from a venous injection, were 
it not for the fact that in the former the main arteries and their branches, 
and frequenly some arterioles and capillaries, are well injected, thus mak- 
ing differentiation comparatively easy. Arterial injections from the 
aorta also differed from most of the venous injections made by puncture, 
in the fact that the injection mass seemed to penetrate the filled blood 
spaces with more difficulty. This result may have been due, however, 
