DEVELOPMENT AND FUNCTION OF HEMAL NODES 379 



capillaries coincident with an absorption of some of the fat, the 

 conversion of the fat cells into reticular cells, ami proliferation 

 of the endothelium into the dilated capilliarics, dividing them up 

 into blood sinuses." Continued lymphoid formation, develop- 

 ment of sinuses and absorption of fat is said to lead to the 

 fully develo]:)ed hemolymph nodes or of the ordinaiy lymphoid 

 glands, ^f the blood sinaises persist the structure of a hemo- 

 lymph node is presented; if, on the contrary, the formation of 

 the lymphoid tissue is so great as to reduce the sinuses to capil- 

 laries the node assumes the structure of a lymphatic gland. 



It is not my purpose to discuss the question of metaplasia 

 or the conversion of such a mature, definitive structure as a 

 fat cell into a lymphocyte or even a reticulum cell — yet it is 

 only just to recall in this connection that the doctrine of the 

 development of lymph glands from fat which is based largely 

 on clinical evidences, on those obtained from pathological speci- 

 mens, and on the older wholly insufficient experimental evidence 

 obtained in one dog by Bayer '85, is to say the least, still sub 

 judice as far as pathological and abnormal conditions are con- 

 cerned and is not proven at all for normal conditions. This 

 statement is made with full knowledge of the thesis of de 

 Groot and the short article of his preceptor Reddingius 

 '12, for their work does not set aside even if it calls in question; 

 the experimental work of Vecchi '11 which confirmed and 

 extended the experiments of Heuter '04 and Meyer '06. More- 

 over, the development of lymph nodes as recently re-investi- 

 gated by Sabin '13, Lewis '09 and others is a totally different 

 one than that indicated by Warthin. Yet my contention is 

 not, to be sure, that what is true for lymph nodes must necessarily 

 hold for hemal nodes or that a course of development normally 

 followed, necessarily must be repeated exactly under pathologi- 

 cal conditions as well, but merely that a development of hemal 

 or of hmiph nodes from fat is not proven. 



Neither does Warthin's mode of development of hemolymph 

 nodes from fat receive any confirmation from the investigation 

 of Sabin '05. In this investigation which has stinmlated so 

 much fine work 8abin stated that the development of hemo- 



