COMPARATIVE HISTOLOGY AND PHYSIOLOGY OF THE SPLEEN. 297 



(d) In early extra-uterine life. 



(1) In the spleen. 



(2) In the bone marrow. 



(e) In adult life. 



(1) In the bone marrow. 



In each one of these situations, at the time when blood formation is known to occur 

 in it, the presence of giant cells has been demonstrated. 



Blood formation in the vascular area is associated with mesoblastic cells, con- 

 taining a central ball of nuclei — the vaso-formative cells of Ranvier.* Similarly, 

 large multinucleated cells or hsematoblasts have been described by WissozKYt in 

 the allantois of the embryo rabbit ; and they are considered by him to produce 

 small uninucleated hsematoblasts — the erythroblasts — by a process of endogenous 

 formation. 



In the liver of the three months' human foetus, Neumann,! m 1874, described 

 appearances of the giant cells which, as he believed, indicate an endogenous develop- 

 ment of nucleated red blood-corpuscles within them — the mother cells. He also 

 alludes § to similar observations by Reichert, who found in the fcetal liver of the 

 hen " mother cells filled with a younger generation." Recently, an able paper has 

 been published by Omer Van der Stricht,|| on the development of the blood in 

 the embryonic liver, in which he states that giant cells appear in the liver at the 

 moment when the organ partakes actively in the formation of red blood-corpuscles, 

 and accounts for the presence of the nuclei of erythroblasts within the giant cells 

 on a theory of phagocytosis. 



The presence of large multinucleated vacuolated cells, tinted with haemoglobin, in 

 the subcutaneous connective tissue, was first described by E. A. Schafer IT in the newly 

 born rat. Within them he described the formation of non-nucleated red blood-corpuscles. 

 If, as would appear from his description, he examined these cells in the fresh condition 

 only, and without staining, the newly formed red blood-corpuscles may have contained 

 nuclei that were not revealed. 



Giant cells in the bone-marrow were first described by Bizzozero ; '** and in the liver 

 and spleen by Kolliker and REMAK.tt The mode of production of red blood-corpuscles 

 from giant cells in the embryonic liver, spleen, and lymph glands, and in the adult bone- 

 marrow, according to the view advanced by Foa and Salvioli, is described by Bizzozero $ 

 as follows : — From the nuclear heap of the giant cell a bud springs ; this, after it has 

 increased in size, becomes isolated, makes its way to the periphery of the cell, where it is 

 surrounded by a layer of hyaline substance derived from the protoplasm of the giant cell, 

 and forms a projecting bud on the surface of the cell ; it ultimately becomes detached as 



* Ranvier (45), p. 640. f Wissozky (42), p. 479. 



X Neumann (28), p. 469. § Neumann (28), p. 448. 



II Van der Stricht (48), p. 60 and p. 88. 1" Schafer (35), p. 243. 



** Bizzozero (31), p. 30. tt Remak (27), p. 99. 

 \\ Bizzozero (31), p. 30. 



