5o 
HEMOLYMPH NODES OF THE SHEEP 
states that there rarely are other transition forms, in which there is a 
mixture of blood and lymph streams in one portion and only lymph in 
the sinuses of the rest of the node, on the other hand ; and cases in which 
both streams mingle in one portion, while the rest of the node contains 
blood sinuses only. 
Vincent also believed in the existence of nodes having sinuses com- 
mon to the lymphatic and vascular systems, as also Robertson had pre- 
viously stated. 
Some of the difficulties in identification met with in gross appear- 
ance are likewise encountered upon microscopical examination of sepa- 
rate sections ; but if a group of mixed or transitional nodes really existed 
with sinuses common to the vascular and lymphatic circulations, it is 
clear that it should be possible to inject both the lymphatics and the 
veins from them. For, as is well known, puncture of a lymph node 
always results in the injection of the lymphatic and not the vascular 
circulation of the node — except accidentally, and only very rarely; 
while, as has been amply established, puncture of hemal nodes, on the 
contrary, always results in injection of the veins draining the node, and 
occasionally the vein draining an adjacent node, but never the lymphatics. 
Hence, if mixed or true hemolymph nodes existed, the injection mass 
should appear both in the vena cava and in the thoracic duct. Such 
was, however, never the case; and after a little experience it was quite 
possible indeed to foresee, in most cases at least, what the results of punc- 
ture injections into a given questionable node in situ on the fresh carcass 
would be. For example, the microscopically pigmented nodes which 
suggest anthracosis, were generally found in connection with the lym- 
phatic system. The same was also true of rare and rather large nodes 
found in the sub-lumbar region in sheep, a portion of which was typic- 
ally lymphatic in color and the rest quite as typically hemal. If these 
large, apparently combination forms, were true hemolymph nodes, it 
should, of course, have been possible to inject at least the lymphatic ves- 
sels from the typically appearing lymphatic portion, and the veins from 
the typical hemal portion. However, this was never possible. Such 
nodes in the sheep were found to be either in connection with the vascu- 
lar or with the lymphatic system, but never with both, and usually with 
the latter; nor has anyone injected the veins from one and the lymphatics 
from the other portion. 
Since the only reliable criterion — the injection method — for distin- 
guishing a lymph from a hemal node, was accepted only as a result of 
experiments, and is not a theoretical or preconceived one, it follows, to 
