LYMPHATIC AND VASCULAR RELATIONS 
33 
under extraordinary circumstances it traversed a system of arterioles 
which form a direct passage between the blood spaces and the lacunae, 
and which he regarded as playing the role of a self-regulatory system. 
According to this conception, for example, if for some reason the pres- 
sure within the node becomes too high, this system of arterioles is sup- 
posed to be thrown open automatically until conditions of normal, or at 
least of a reduced pressure, again obtain. Even granting the existence of 
such a self-regulatory system, I have been unable to confirm either the 
occurrence of arterioles uniting blood spaces and venous lacunae, or the 
occurrence of the thickenings in the walls of capillaries by means of which 
this regulatory function is supposed to be effected. Moreover, it is more 
than likely that if such connecting arterioles existed in any number one 
might reasonably expect the blood spaces and these arterioles, rather than 
the lymphatic tissue between lacunae and blood spaces, to become injected. 
This is, however, not the case. 
If the calibre of an artery supplying a node is compared with the 
area of the intranodal venous system, it is evident that the intra-venous 
circulation must of necessity be a very sluggish one, although increases 
in pressure might nevertheless slightly accelerate the intra-nodal cur- 
rent. This would of course be true, even if not nearly to the same ex- 
tent, whether the circulation is a closed or an open one. This supposed 
sluggishness of the current is confirmed by the results of injections from 
the aorta, for it will be recalled that small lymph nodes manifested color 
changes almost instantly, and that the finest capillaries were later found 
to contain injection mass, while many of the hemal nodes remained unin- 
jected, and only a few manifested slight color changes. Consequently 
it seems to me that if arterioles connected the blood spaces and venous 
lacunae, one might reasonably expect them to become injected, even if 
not as readily as the capillaries in lymph nodes. Besides, if the arterial 
capillaries opened directly into the parenchyma, or if other than indirect 
communications between the blood spaces and lacunae existed, it would 
be difficult indeed to explain why blood should accumulate within the 
node, as it usually does. It is also evident that if the disposition of the 
vascular circulation in hemal nodes were comparable to the lymphatic 
circulation in lymph nodes, it should not be so exceedingly difficult to 
inject hemal nodes from the aorta ; for the ease with which lymph nodes 
can be injected from the periphery, and the speed with which they man- 
ifest color changes are, of course, striking. Hence it seems to me that 
these considerations alone suffice to establish the fact that the relation of 
the peripheral and central blood spaces to the veins of hemal nodes must 
be essentially different from that of the lymphatic vessel to the peripheral 
and central sinuses of lymph nodes. 
