38 
HEMOLYMPH NODES OF THE SHEEP 
they are usually empty save for small amounts of granular material 
(fig. 21 ), it is clear from this and other direct evidences that they com- 
municate rather freely with the large central venous spaces and the drain- 
ing veins. That they must, however, also communicate in some manner 
with the lymphatic tissue and the blood islands and blood spaces, is indi- 
cated by such appearances as those represented in fig. 20, and by the 
results of many puncture injections, as well as by other considerations. 
While, then, it was comparatively easy to determine the direct con- 
nection between lacunae and veins, microscopically alone, their relation- 
ship to arteries could be demonstrated satisfactorily only by injection 
methods, for no matter how close to a lacuna the arterial terminations 
were, they were only seldom seen to open directly into them (fig. 23). 
Nor was it easily possible to demonstrate a direct communication be- 
tween venous lacunae and the blood islands or blood spaces (fig. 24), or 
between them and the peripheral or subcapsular blood space, except in 
nodes whose structural relations had been profoundly altered as a result 
of decided depletion of the lymphatic tissue. But even in most of these 
specimens a narrow and more or less perfect barrier of lymphatic tissue 
almost invariably separated them from the blood islands or blood spaces 
(figs. 13, 21 and 22). The existence of these barriers of lymphatic 
tissue between the venous lacunae and the peripheral blood space on the 
one hand, and the central or internal blood spaces or blood islands on the 
other, as well as the almost constant presence of an amorphous or slightly 
granular deposit in many of them, even in the case of nodes practically 
devoid of lymphatic tissue, are particularly significant, it seems to me, for 
the elucidation of the somewhat obscure circulatory conditions. Besides, 
that the interpretation of these venous spaces or radicles as lymphatic 
spaces, however excusable, is erroneous, must be evident from the above 
experiments and observations. 
In some depleted nodes, and very rarely also in others, large con- 
nective tissue septa divide the node so completely that the individual sub- 
divisions might almost be considered as separate nodes (fig. 16) ; but 
no specimens were found in which the lymphatic tissue could be said to 
be fibrous or muscular, as stated by Vincent and Harrison [28]. Indeed, 
in the great majority of cases, there are no evident septa or trabeculae 
extending inward from the capsule and subdividing the node. The 
coarser reticulum, however, is generally plainly visible in the peripheral 
blood space, in many blood islands (fig. 25), and throughout depleted 
nodes, by means of low magnification. That this reticulum is more con- 
spicuous in the peripheral blood space is, of course, due to the fact that 
