260 VERA DANCHAKOFF 



organs of the adult organism. Dominici (10) admitted in his 

 paper ('01) that cells with the structure of small lymphocytes 

 give rise to the myeloid tissue. ^'Les petits mononucleaires 

 en question (in another part of his paper he uses the term of 

 small lymphocytes) ont des dimensions egales ou inferieures a 

 celles des hematics : un noj^au rond, une bordure protoplasmique 

 mince. Un element figure, offraiit de tels attributs, n'est ce pas 

 ce que I'on a denomme communement une cellule embryonnaire?" 

 A closer study of the embryogenesis of the blood tissue would 

 certainly not have allowed Dominici to consider the small lym- 

 phocytes as being young embryonic cells, for the cells bearing the 

 structure of small lymphocytes appear in the organism consider- 

 ably later than other lymphatic cells, at least in mammals, birds 

 and reptiles. Though the stem cells of the myeloid tissue, 

 according to Dominici, bear a morphological structure identical 

 with cells, which differentiate into lymphatic tissue, he still 

 attributes to the myeloid stem cells specific potencies of differ- 

 entiation, which they preserve from early embryonic period. 

 Eater, in 1909, Dominici (10) changed his opinion and attributed 

 to the lymphatic tissue itself the faculty of myeloid transform- 

 ation. Dominici was thus first to stand for the conception of 

 autochthonous development of the myeloid tissue in the lymph- 

 atic organs. 



According to Ehrlich (13) the myeloid tissue, which appears 

 under certain pathological conditions in different parts of the 

 adult organism, derived from the central myeloid organ, namely 

 from the bone-marrow. This opinion was expressed by Ehrlich 

 at a time when the differentiation of every blood-cell seemed to 

 be predestined generations back by the specific constitution of 

 their ancestral cells. Ziegler (47) and Helly (19) still adhere to 

 this view. They base their opinion upon the occurrence of bone- 

 marrow Ausschwemnaungen, which follow venous injections of 

 parenchymal mash, also after bone-marrow traumas. Helly 

 finds support to his view also in the fact that after 



Beeinflussung des Knochen-marks mittels Bakterien schon nach 

 kurzer Zeit in der Milz des Kaninchens, welche unter normalen Ver- 

 haltnissen so gut wie gar keine specifischen Markelemente j lingerer 



