HEMOLYMPH NODES OF THE SHEEP 
changed them into ordinary gray lymph nodes ; while prolonged absti- 
nence, on the contrary, resulted in the accumulation of erythrocytes in 
lymph nodes. 
From these considerations it is evident that many morbid and abnor- 
mal conditions can cause an accumulation of blood cells in the paren- 
chyma and sinuses of lymph nodes, and that blood cells are probably con- 
stantly present in the lymph of many, if not of all mammals. From 
observations made especially on dogs the writer is also convinced that 
there often is a retrogression, or better a diffusion, of blood from the large 
veins into the large lymphatic trunks at points of juncture, which can 
convert many of the bronchial and mediastinal lymph nodes into so-called 
hemolymph nodes. t The distance to which this reflow or intermixture of 
venous blood — or suspensions and solutions injected into the veins — can 
extend into the lymphatics is truly remarkable, and is discussed more 
fully in an article on the hemal nodes of dogs, cats, etc. A similar retro- 
grade flow of chyle was noticed in several instances from the large ab- 
dominal lymphatics to the external iliac trunks almost up to the inguinal 
ligament in dogs. It should also be recalled in this connection that un- 
usual lymphatico-venous connections may rarely be a factor in the pro- 
duction of hemorrhagic lymph nodes. It is not my aim to open an old 
controversy regarding lymphatico-venous communications, but the evi- 
dences recently brought forward by Huntington [na] in Macropus rufus, 
by McClure and Silvester [16] for primates, carnivora, rodents, ungu- 
lates and marsupials, by Silvester [26] for the monkey, and by Baum [1] 
for bovines, seem to confirm, in a measure, the early observations of 
Wutzer, Nuhn, Petrel, Kaaw, Kulmus, Lohmann, Fauth, J. Miiller, Pan- 
izza, Meckel Sr. and Jr., Steno, Nuck, Pequet and others on man and ani- 
mals which a partly justified skepticism has so far obstinately refused to 
accept. The writer has not much confirmatory evidence, but it is 
clear that where a lymph node is intercalated in a lymphatic circuit, 
in such a way as to have a double communication with the veins, retro- 
grade diffusion of blood from the peripheral vein through a short efferent 
lymphatic into the node can easily convert all nodes lying more centrally 
on the lymphatic circuit into reddened lymph nodes, because of an inter- 
mixture of blood and lymph in the sinuses of the more centrally placed 
lymph nodes. Such a case was actually observed by the writer in a lamb 
in the case of an axillary lymph node on each side. 
f Although Retterer (Comptes Rendus de I' Assoc. des Anat., Lyon, 1901) re- 
jects such an explanation in referring to a similar explanation made by Thomas 
Bartholin, I am certain that a reflow or diffusion of blood from the large veins 
into the lymphatics occasionally occurs. 
