DEVELOPMENT AND FUNCTION OF HEMAL NODES 381 



If I understand Sabin correctly the hemal and hemolymph 

 nodes or glands are identical structures and begin their develop- 

 ment in i-e.lation to a plexus of veins just as the lyinph nodes 

 do to a plexus of Ij^anphatics, but the peripheral sinus of the 

 former is formed from veins. However, the interpretation of 

 Sabin's statement to the effect that hemal or hemolymph nodes 

 begin their development exactly as lymph nodes do except that 

 the peripheral sinus of the former is formed by veins, would 

 also seem justified. 



According to Retterer '07 the ordinary lymph gland begins 

 its development in a hemolymphatic state, both white and red 

 cells being formed therein. Hence Retterer regards all lymph 

 glands as having been 'hemol>anphatic glands' originally, and 

 asserts that those w^ho think there are two classes of glands 

 do not even suspect that wholl}^ without experimental inter- 

 ference, it is easy to convert one and the same gland into a 

 'leucolymphatic' or ordinary white or gray gland, or a 'hemo- 

 l^inphatic' or red gland by simply varying the conditions of 

 alimentation. It would seem that the effects of starvation on 

 lymph nodes even if transient as is probably the case, are too 

 well known to need emphasis here. The effects of bleeding and 

 of obstruction of the lymph and blood stream not to mention 

 disease, are of course known still better to almost everyone. 



If I understand Retterer correctly the terms lymph and hemo- 

 hanph merely designate different physiological states of one 

 and the same node, and the inability to demonstrate lymph 

 vessels in the hemal nodes of sheep, is due merely to the practical 

 difficulty of injecting the l^rmphatics. Be this as it may, to 

 be wholly consistent Retterer should, of course, apply the same 

 reasoning to the spleen and to supernmnerary spleens. 



As far as transformation of hemal into lymph nodes is con- 

 cerned it follows, to be sure, that this is an impossibility unless 

 (1) afferent and efferent l>anphatic vessels grow into the hemal 

 node; unless (2) the circulation of hemal nodes is transformed 

 into a closed one; unless the obliteration of blood spaces and 

 lacunae or the conversion of the latter into capillaries is effected 

 and unless (3) the isolated erythrocytes and large areas of the 



