DISTRIBUTION, OCCURRENCE AND APPEARANCE 
9 
flattened on the sides sustaining the greatest pressure, and resembled 
lymph nodes somewhat more closely in shape. Occasionally a group of 
nodes, or a single node, was found, which looked like a mass of beaded 
blood vessels, the contiguous walls of which had fused. In other cases 
isolated nodes were found from which a beaded vessel or vessels (figs. 
I and 2) closely simulating a lymphatic vessel in form, but dilated with 
blood, could be seen plainly for some distance from the node, as noted by 
Weidenreich. In still other instances the appearance was that of a blood 
vessel of somewhat varying calibre, which formed a loop with local thick- 
enings. Pressure upon these nodular areas of the vessels would easily 
bring about complete collapse in the area of pressure, followed by sub- 
sequent refilling with blood. This effect is in marked contrast to the re- 
sults of pressure upon hemolymph nodes of any size and location, for 
these could never be reduced appreciably in size even if subjected to 
strong pressure. Instead of collapsing they would invariably burst. In 
some cases these nodular complexes were formed by a number of small 
nodes which lay in close proximity to each other, or had become more 
or less completely fused. (Figs. 3 and 4.) Further reference will be 
made to these later. 
Since the descriptions of the external appearance of hemolymph 
nodes found in the literature on the subject are quite adequate, this mat- 
ter will be discussed here only in a purely incidental way. Intra vitam 
and not long post-mortem hemolymph nodes usually have the dark 
color of moderately venous blood. Rarely, however, light cherry red 
and scarlet nodes are seen. These are generally small, and lie immediate- 
ly beneath the peritoneum. The prevailing color in fresh carcasses, how- 
ever, varied from a bright red to dark chocolate, or even dull black. As 
pointed out by Robertson [24], this variation is probably chiefly due to 
differences in the degree of post-mortem oxygenation of the blood within 
the node. That this assumption is correct was shown by the fact that 
dark-colored nodes quickly turned to a bright red color when exposed to 
the air, provided of course that access to them was not made too difficult 
by the presence of a thick overlying layer of fat, or by the drying of the 
overlying peritoneum and capsule. This change to a bright color upon 
exposure is greatly accelerated by stripping the peritoneum overlying 
the node, or, still better, by exposing the node to pure oxygen. That 
this color change progresses gradually from the exterior to the interior 
can also be shown by sectioning nodes which have been exposed to the 
air or oxygen for varying intervals of time. Such sections show that the 
outer bright-red layer varies in thickness within limits, with the length 
