in the size of the cells, many of the smallest specimens would be 
indistinguishable even microscopically. Nevertheless, the sites of predi- 
lection are wholly different and taken as a class the hemal nodes of 
the sheep differ from spleens in several essential respects though 
showing with them a tendency to grouping and budding. Save for 
an occasional specimen which resembles the spleen quite closely in 
external appearance and in microscopic structure as well the hemal 
nodes of the sheep usually contain a more or less complete so-called 
peripheral sinus or better subcapsular blood area or space and in the 
parenchyma internal to this a series of communicating true venous 
sinuses devoid of reticulum which may form a complete circuit in 
section and communicate with similar more centrally placed sinuses 
or lacunae. Hemal nodes, as a rule, also contain a number of other 
areas of erythrocytes — the blood areas in the parenchyma generally 
spoken of quite incorrectly as sinuses — in which practically nothing 
but erythrocytes and reticulum are seen. These are not so common 
except in small spleens in which the entire organ may often be con- 
sidered as a single mass of blood and reticulum containing some 
leucocytes. Moreover, lymph follicles with a central artery, resembling 
Malpighian corpuscles at all closely are found only very exceptionally 
in hemal nodes and many of the latter in the sheep also contain 
numerous eosinophiles of various kinds which were never noticed in 
the supernumerary spleens in even approximately corresponding numbers. 
Areas of the parenchyma which have the structure of the so-called 
splenic pulp are usually absent but since many — most? — of the 
supernumerary spleens do not contain portions of parenchyma corre- 
sponding to pulp and especially since this is true also of many por- 
tions of the main spleen of the dog and cat it would not be just to 
emphasize such a distinction. Hence until more is known regarding 
the genesis of supernumerary spleens and hemal nodes the fact that 
the former are restricted to the abdominal cavity while the latter are 
found even subcutaneously in bovines, makes one hesitate to pronounce 
in favor of their morphological indentity in spite of their close resem- 
blance. It would, of course, not be well to over-emphasize a mere 
matter of location or the fact that a peripheral sinus and comparable 
venous lacunae which are so commonly present in hemal nodes, were 
never seen in supernumerary spleens but these differences are probably 
not inconsequential even if not fundamental. However if, as seems 
likely, supernumerary spleens as here described do not necessarily 
