No. I.] BLOOD CORPUSCLES. gr 



fact has been abundantly confirmed by all observers since Kol- 

 likcr's time, and is capable of easy demonstration. The way in 

 which the red corpuscles develop in the liver has not, as far as 

 I know, been described in any detail. Kolliker held simply 

 that the liver contained certain nucleated white corpuscles 

 which become transformed to red corpuscles by the develop- 

 ment of haemoglobin, and which subsequently lose their nuclei. 

 Neumann (5^/) states that he finds in the liver nucleated red 

 corpuscles in greater numbers than can be accounted for by 

 supposing that they are carried there by the splenic veins and 

 other vessels opening into the liver. They must be formed in 

 the liver then de novo, and he suggests at least two methods by 

 which they are produced. First by endogenous formation in 

 certain large cells. A number of nuclei arise in these cells by 

 a process of endogenous division, and a homogeneous yellow 

 substance collects round each nucleus. Each nucleus with its 

 surrounding colored protoplasm constitutes a red corpuscle, and 

 this is afterwards liberated and undergoes its further develop- 

 ment. In addition he finds in the embryonic liver a number 

 of free nuclei which are undoubtedly the same in structure as 

 the nuclei of the nucleated red corpuscles. How these free 

 nuclei arise, and what becomes of them, he leaves undescribed, 

 but supposes that they represent one step in a second method 

 of production of nucleated red corpuscles. He seems to sug- 

 gest, indeed, that the free nuclei form round themselves a pro- 

 toplasmic envelope in which hfemoglobin is afterwards devel- 

 oped, and in this way they are converted to nucleated red 

 corpuscles, — a view which, as we will see, has been proposed 

 by others to account for the formation of new corpuscles in the 

 marrow in post-natal life. Neumann says, moreover, that a 

 new development of capillary blood-vessels is taking place in 

 the liver throughout almost the whole of embryonic life, and 

 in some way the formation of the new red corpuscles is con- 

 nected with the existence of these newly forming blood-vessels. 

 Foa and Salvioli (13) believe that the nucleated red corpuscles 

 found in the liver are derived from colorless corpuscles, — " hya- 

 line cells," — which in turn arise by constriction or segmentation 

 from the large giant cells found in the liver. It is undoubtedly 

 true that in the embryonic liver the nucleated red corpus- 

 cles are formed from colorless cells. Whether one studies 



