166 JOHN STEPHENS LATTA 



The large (clear-nucleated) cells of the lymphatic nodules, 

 lymphoid hemoblasts, have been described under various names 

 by investigators of problems of blood-cell formation. This 

 type of cell is identical, morphologically at least, with the free 

 wandering cells of the loose connective tissue, the so-called pri- 

 mare Wanderzellen of Saxer ('96), the primitive large lympho- 

 cyte or wandering cell of Maximow and others, hemogonia of 

 Mollier ('13), lymphoblast of Naegeli, mesameboid of Alinot, 

 lymphoid hemoblast or hemocytoblast of Danchakoff, etc. 



The term, proposed by Danchakoff, seems to be the most 

 descriptive of this type of cell, for, as she pointed out when sug- 

 gesting this term, it is essentially of a lymphoid nature, and it is 

 quite generally accepted (monophyletic theory) that this type 

 of cell possesses potentialities capable of transforming into any 

 of the many difTerent cellular elements of the blood under favor- 

 able environmental conditions. Although environmental condi- 

 tions are normally such, in lymphatic nodules, that this type 

 of cell remains as a cell of the lymphocyte series, it is believed to 

 retain this potentiality of further differentiation into other types 

 of blood cells (as in one instance, noted by the writer, in which 

 all the lymphoid hemoblasts of a lymphatic nodule of Peyer's 

 patch in a twelve-day-old rabbit had transformed under path- 

 ological change of environmental conditions into eosinophilic 

 granular leucocytes). The term, lymphoid hemoblast, will in 

 this article refer to this type of cell. 



Hematologists are practically united in ascribing to this cell 

 an origin from the fixed cells of the body mesenchyme, or embry- 

 onic connective tissue, Danchakoff maintaining that they may 

 also derived from cells of the vascular endothelium. 



But the origin of the small lymphocytes, their potentialities, 

 and relation with the lymphoid hemoblasts are yet much debated 

 questions. Macimow thought the small lymphocytes and lym- 

 phoid hemoblasts or large lymphocytes were one and the same 

 cell in different growth stages. Badertscher ('15) found, in the 

 developing thymus, that the small lymphocytes were derived by 

 repeated divisions of ' large lymphocytes, ' but is not sure whether 

 the small lymphocytes may again grow into the other type or not. 



