192 George 8. Huntington and Charles F. W. McClure. 
microscopical field. We have had no personal experience with the 
injection method, as practised by Professor Sabin and others, 
but have had the opportunity of seeing at a meeting of the Anatom- 
ical Association a number of her series sectioned after injection. 
The chance of extravasations of the injection fluid, coupled with 
the further chance of injury in section-cutting, seems to us to 
preclude the possibility of drawing definite conclusions by this 
method as to the communication or non-communication of 
venous and lymphatic spaces. The close approach in many in- 
stances of the blind ends of the lymphatic sac to the angles of 
venous confluence and the delicacy of the intervening tissue, 
raises the possibility of a rupture occurring, to a probability, if an 
injection were made in either direction. However valuable the 
injection method may prove in determining the extent and fur- 
ther growth of the lymphatic system when once established, we 
have felt that it would not yield trustworthy results in determining 
the problem now under consideration. On the other hand, in 
view of the uncertainty of injections, it is evident that even a 
negative result would not be conclusive and could not be accepted 
as valid evidence that the lymphatic sae no longer communicated 
with the venous system. 
We are obliged, therefore, in the present state of our knowledge, 
to confine ourselves to the above statement, viz., that, as far as 
observation can determine, an intermediate stage exists in 
which temporarily the lymph sac is completely separated from the 
venous system, with which at a later period it makes secondary 
connections which constitute the definite and permanent adult 
lymphatico-venous taps. 
As bearing somewhat on this question, the conditions noted 
above in the adult cat (ef. p. 188) deserve further consideration. 
While in many individuals both the common jugular and jugulo- 
subclavian taps are present (fig. 3), others possess only a single 
adult lymphatico-venous connection on each side (fig. 1), which 
may be located at either one of the two typical points. We con- 
sequently deal in these latter cases with instances in which one or 
the other of the primitive taps (always present in the early veno- 
lymphatie stages) is given up during the process of development 
