272 VEEA DANCHAKOFF 



and one colored plate is added, as example of the preparations, 

 from which the ink drawings were made. The photographs on 

 plates 1 and 2 were kindly made by Mr. Schmidt of the Illus- 

 tration Department of the Rockefeller Institute. 



Since the nomenclature in the hematology has become nowa- 

 days extremely complex and often under one name different 

 cell units are understood, or even oftener one cell unit is termed 

 by different names, it is useful to state in advance what termin- 

 ology will be used in this paper. 



The stem cells of the different blood elements, which first 

 appear after isolation of the blood-islands, have the structure 

 of the well-known large lymphocytes. The term of large lymph- 

 ocytes was appUed for these cells by Pappenheim (33), Dan- 

 chakoff (9) and Maximow (25). Studies of hematopioetic tissue 

 led to recognize everywhere cells of the structure of large lym- 

 phocytes and to identify them as stem cells for the blood tissue. 

 Only few differentiation potencies were first assigned to the large 

 lymphocytes. This however corresponds but little to the various 

 differentiation potencies, exhibited under different conditions 

 by this cell. So the name of large lymphocyte seemed to cor- 

 respond little to the given cell in its new conception. Since 

 personal studies did not give me any data, bestowing all the 

 lymphatic cells with equal potencies, the less appropriate seemed 

 to me the name of large lymphocyte in connection with the 

 stem cell for different blood elements. In my last papers I 

 called the stem cell, which in itself is a good name, lymphoid 

 hemocytoblast — lymphoid in order to take into consideration 

 its morphological structure, hemocytoblast on account of its 

 potencies to differentiate into various blood cells. The same 

 name will be used throughout the paper. The names of erythro- 

 blasts and erythrocytes do not require any explanation. 



The names of myeloblast and myelocyte seem to me unfitted 

 for the purpose used. This name is wrongly applied to cells 

 which neither appear first in the bone-marrow, nor are cell 

 units exclusively characteristic of this organ at any time of its 

 existence. These terms will be substituted, as in my previous 

 papers, by granulocytoblasts and granulocytes or leukocytes. 



