400 AKTHIHi AVILLIAM MEYER 



Although lymph vessels cmii be observed in the \'iciiiiiy of de- 

 velopiiip; heinal nodes I have never seen them come into rela- 

 tion to them nor have I ever seen a hemal node form in or about 

 a lym])hatic' or vascular plexus. The hemal node then from 

 its beginning is intercalated in the vascular not the lymphatic 

 system. 



Clarkson working on the horse, sheep and pig and some of 

 the earhest observers and very recently also Meek '10 working 

 on the pig thought that hemal nodes were the seat of formation 

 of erythrocytes as well as of leucocj^tes. Robertson '90. e.g., 

 strangel}" enough, thought that the nuclei of cells which looked 

 like large multi-nucleated leucocytes, became erythrocytes while 

 Meek '10 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, prehap«, fifty closely-packed 

 normoblasts, another a clump of myelocytes, neutrophylic 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 '00, the stages in 

 the formation of erythrocytes had not been observed in develop- 

 ing nodes even. However, Drummond too believed that hemal 

 nodes exercised some function in connection with erythrocyte 

 and suggested that this function might by a cyclical one. This 

 conclusion of Drummond's was based on the great variability 

 in cellular content. These variations within the same or in 

 different species, he believed to be due to varying rates of blood- 

 cell destruction. Drummond further thought that the rate 

 of destruction of erythrocytes within the individual node or 



