6o 
HEMOLYMPH NODES OF THE SHEEP 
be exceedingly active, even while the node is depleted rapidly. Hence 
such a node might really be in a state of regeneration and of hyperactivity, 
while appearing exhausted and depleted and hence inactive. But the 
most obvious objection to a physiological classification of hemal nodes lies 
in the fact that all manner of structurally transitional forms — i. e., active 
and inactive — occur if a microscopical examination of uninjected speci- 
mens is to form the criterion. Hence in the present state of our knowl- 
edge — or, better, ignorance — all attempts to subdivide hemal nodes into 
a number of definite classes must, it seems, remain entirely futile and 
wholly unjustifiable from all standpoints, even if some time ago both 
Lewis and Warthin stated that certain classes of hemal glands were lim- 
ited to certain species. 
Functions 
Clarkson, working on the horse, sheep and pig ; and some of the ear- 
liest observers, and very recently also Meek [17], working on the pig, 
thought that hemal nodes were the seat of formation of erythrocytes as 
well as of leucocytes. Robertson, e. g., strangely enough, thought that 
the nuclei of the large multi-nucleated leucocytes became erythrocytes; 
while Meek, writing about conditions found in the hemal nodes of the pig, 
says: "Of special interest are certain small islets of cells which occur in 
the midst of the blood in the sinuses. They are sharply defined from 
the surrounding red blood corpuscles, and are formed from aggregations 
of various types of blood cells. One such focus will contain, perhaps, 
fifty closely-packed normoblasts, another a clump of myelocytes, neutro- 
phylic in granulation, while yet others are made up of aggregations of 
polymorphonuclear cells. Mitotic figures may be seen in the cells of these 
islets." . . . "The above appearances would seem to suggest that a 
part at least of the function of these glands in the pig is concerned with 
the formation of blood cells, red and white ; and they are described at 
some length, as they differ materially from the conditions found in any 
human hemolymph glands examined." These observations of Meek are 
unique, for, as emphasized by Drummond [5], the stages in the formation 
of erythrocytes had not been observed in developing nodes even. How- 
ever, Drummond too believed that hemal nodes exercised some function 
in connection with erythrocytes, and suggested that this function might 
be a cyclical one. This conclusion of Drummond was based on the great 
variability in cellular content; which variations, within the same or dif- 
ferent species, he believed to be due to varying rates of blood cell destruc- 
tion. Drummond further thought that the rate of destruction of erythro- 
cytes within the individual node or species, was dependent upon the num- 
