No. I.] BLOOD CORPUSCLES. yj 



blasts have a nucleus which shows always a chromatin reticulum, 

 but no true nucleolus. They never make amoeboid movements 

 nor ingest foreign particles, and finally they develop haemo- 

 globin in the cell substance, passing thus into nucleated red 

 corpuscles. Cell division takes place with the formation of the 

 usual karyokinetic figures. Lowit designates this method of 

 multiplication as divisio per fila, in contradistinction to the 

 method found in the leucoblasts. He states that he has never 

 been able to find transitional forms between the two kinds of 

 cells, though in the organs in which they occur they are found 

 freely intermingled with each other. The leucoblasts enter 

 the lymph stream, and eventually reach the blood as uninucle- 

 ated leucocytes. These are rather small, and are devoid of the 

 power of making amoeboid movements, — a fact which was 

 pointed out long ago by Schultze. In the blood stream, they 

 increase in size, the nuclei become elongated and constricted, 

 and finally fragment to form the so-called multinuclear leuco- 

 cytes. He believes, then, with many others that the multinu- 

 clear leucocytes are not cells in the act of multiplication, but, 

 on the contrary, are disintegrating ; and the multinuclear stage 

 so-called is probably followed by a complete dissolution of the 

 cell. 



In the veins coming from the blood-forming organs the imi- 

 nucleated leucocytes predominate greatly in number. In the 

 right heart the number of uninucleated forms is still relatively 

 large, while in the left heart they become less numerous, and 

 in the peripheral arteries they show a striking diminution. In 

 other words, the transition from the uninucleated to the mul- 

 tinucleated forms takes place chiefly in the venous system 

 during the brief interval of time required for the blood in the 

 veins to pass from the lymphoid organs to the left heart. The 

 erythroblasts, after the development of haemoglobin, become 

 nucleated red corpuscles. In the marrow of the bone all the 

 intermediate stages may be obtained without difficulty. So in 

 the liver and spleen of the foetus and in the spleen of the adult 

 in some cases after severe hemorrhage similar transitional 

 forms are found. But in the lymph glands transitional forms 

 between erythroblasts and nucleated red corpuscles cannot 

 be obtained. Hence he concludes that the transition in this 

 case takes place in the lymph stream or the blood or both. 



