268 
arise from individual preformed Anlagen which are to be considered 
as fragments of the Anlage of the main spleen there is little reason 
for regarding them as distinet from hemal nodes. That the latter and 
spleens are analogous structures one can scarcely doubt but the 
evidence as to their origin is not sufficiently convincing to prompt 
me to assume a similar origin for both or to regard their formation 
de novo as established. 
Elsewhere?) various explanations have been given for the occur- 
rence of reddened lymph nodes. In addition to what has been said 
there it should be noted that in dogs and cats these reddened nodes 
are found more frequently in certain locations. This is true especially 
of the lymphoglandulae sternalis cranialis and to a lesser extent also 
of some of the mediastinal, bronchial and mesenteric nodes. Nor is 
it uncommon to find the communicating lymph vessels tinged or even 
filled with biood which in some cases, undoubtedly entered the lymph- 
atics at the cervical lymphatico-venous junction and diffused into or 
even beyond the first thoracic nodes. That this explanation is correct 
is easily established by the injection of comparatively small quantities 
of suspensions of India ink in distilled water at these junctions. In 
many instances the ink will easily pass into the lymphatics and in 
the course of half an hour will have reached some of the nodes. 
While it may be urged against these conclusions that phenomena seen 
post mortem do not necessarily occur intra vitam the retrogression 
of chyle occasionally seen in the unobstructed lumbar lymphatics of 
dogs splendidly confirms the explanation and observations offered 
above. Besides the ease with which the thoracic duct is occasionally 
injected from the pad of the foot in the cat and the frequency with 
which a number of lymph nodes arranged in series can often be in- 
jected from one of them in both dogs and cats, seem to indicate that 
lymph nodes in which a large peripheral sinus communicates freely 
with both afferent and efferent lymphatics are comparatively common 
in these animals. As a result of observations made incidentally in 
connection with these studies on hemal nodes it is also evident that 
a comparatively easy path of communication often exists between the 
mesenteric and mediastinal and bronchial nodes in these animals. 
These make it possible, for example, to inject the thoracic nodes from 
the mesenteric while injecting the thoracic duct at the same time. 
1) Meyer, Am, Jr. Anat. 1913. — Jr. of Exp. Zool. 1914. 
