MIXED NODES 
47 
methods were used and repeated examinations made; and pigmented 
cells were seen but seldom. In the search for iron, for example, all 
known methods were used, without a single positive result being obtained. 
However, since Weidenreich [38] found lumps of pigment of a brownish- 
yellow color which gave the reactions in sections treated for inorganic 
iron with, ferrocyanide and hydrochloric acid and also with ammonium 
sulphohydrate, it is possibe that there is considerable variation with re- 
spect to the presence of iron, or that the nodes under observaion were not 
hemal nodes. This supposition also receives some support from the ob- 
servation of Weidenreich that only a particular type of cell, designated 
as a "direct hemophage" by him, contained inorganic iron. I am con- 
vinced, however, that not every cell which might justly be regarded as a 
direct hemophage gives the ferro-cyanide-iron reaction. In fact none of 
these cells, in the large series of nodes examined, gave this reaction. In 
the search for other pigment no special methods were used, since ample 
opportunity for its detection was afforded by the many different methods 
of fixation and staining used. The great majority of hemal nodes con- 
tained no pigment ; but a group of peculiar and uncommon lymph nodes, 
which will be discussed presently under the designation of mixed nodes, 
contained very much pigment. However, only about a dozen of these 
nodes were found, among many hundred specimens examined. Indeed, 
the absence of pigment is an important characteristic of typical hemal 
nodes, and is particularly interesting because such decided destruction of 
erythrocytes apparently occurs in so many of them, v Schumacher 
too called attention to the fact that pigment is usually absent in the hemal 
nodes of the sheep. 
The Question of Mixed Nodes 
As already stated and emphasized, the exceedingly protean character 
of hemal nodes often makes it difficult or impossible even to distinguish 
them from lymph nodes by inspection, or even by microscopical examina- 
tion of a few sections. Because of this difficulty, no doubt, the supposition 
that mixed or true hemolymph nodes exist seemed justifiable to many 
investigators. Helly [n], Forgeot [6 and 7], and v Schumacher 
[27], for example, stated that all transitions can be found in the sheep, 
from glands with lymphatics to those without them. Warthin [34] and 
35] made a similar statement regarding lymph nodes in general; and 
Forgeot even insisted that injections are unnecessary to demonstrate the 
presence of lymphatics in hemolymph nodes. Forgeot nevertheless 
stated that hemolymph glands may be wholly without lymphatic connec- 
tions, and also that the lymphatics join the developing hemolymph node 
