40 
HEMOLYMPH NODES OF THE SHEEP 
change from pure lymphatic tissue to the blood contained in the blood 
spaces could be seen. These transitional areas strikingly demonstrated 
the relations existing between blood islands or spaces and the parenchyma 
of the node, and in them it was easy to see that the blood in the blood 
islands had probably merely replaced the lymphocytes. 
Aside from small quantities of plain muscle found near blood vessels, 
none was observed save in the capsule, where a few fibers could occasion- 
ally be distinguished, but these too were probably associated with blood 
vessels. Hence the conclusion that involuntary muscle is a purely inci- 
dental constituent of the hemal nodes of the sheep, seems justified; and 
the statement that hemal nodes can alternately contract and relax, seems 
a highly fanciful conception, except in so far as such alternations in vol- 
ume may be the result of a varying pressure or fluctuations in calibre of 
the arteries. I am fully aware that these observations are somewhat at 
variance with those of Robertson [24], Weidenreich [37] and v Schu- 
macher [27]. According to Weidenreich unstriated muscle and a few 
elastic fibers are found, especially in the inner layers of the capsule. Both 
Weidenreich and v Schumacher state, however, that these constituents 
vary greatly in amount ; and the former adds that smooth muscle was not 
found in the lymphatic tissue. 
Although sections taken from a number of nodes were stained with 
different elastic tissue stains, undoubted elastic tissue fibers were never 
found. However, since all stains used for this purpose also stain the 
reticulum to some extent, it is practically impossible to differentiate these 
two kinds of fibres definitely by the ordinary elastic tissue stains. More- 
over, the fine reticulum fibers which are very numerous often branch and 
have a wavy outline so as to simulate elastic tissue fibers very closely. 
Hence the evidence obtained in this investigation is an entirely negative 
one as far as the occurrence of elastic tissue is concerned. 
Neither could fat cells be demonstrated in the parenchyma of a num- 
ber of nodes examined after the use of special methods of fixation and 
hardening, such as those of Vom Rath, Flemming, Herxheimer, Her- 
mann, or by the use of osmic acid. Negative results were also obtained 
with Herxheimer's stain as modified by Bell. The only nodes in which 
there seemed to be a rather ill-defined line of demarcation between the 
parenchyma and the surrounding fat were developing nodes, or specimens 
in which the generally inconspicuous capsule was extremely thin in some 
places. These observations regarding the relation of the fat, made on 
several hundred nodes taken at random from a large series of carcasses of 
sheep, bovines and goats, stand in striking contrast to those of Meek [17] 
