14 ORIGIN OF THE RED BLOOD-CORPUSCLES. 



of these cells resembles that of lymph-corpuscles. Long rod-like 



nuclei lie within these 

 cells (K, K), and also 

 red blood - corpuscles 

 (r, r), and both are sur- 

 rounded with proto- 

 plasm. These vaso- 

 formative cells give off 

 protoplasmic points 

 and processes (a, a), 

 some of which end 

 jjij 5 free, while others form 



a network. Here and 

 Formation of red blood-corpuscles within "vaso- , 



formative cells," from the omentum of a rabbit there elongated con- 

 seven days old. r, r, the formed corpuscles. K, K, nective tissue-corpus- 

 nucleiof the vaso-formative cell, a, a, processes cles lie on the branches, 

 which ultimately unite to form capillaries. ^ ultimate]y form 



the adventitia of the blood-vessel. 



The vaso-formative cells have many forms : they may be elongated 

 cylinders ending in points, or more round and oval, resembling 

 lymph cells, or they may be modified connective tissue-corpuscles, as 

 observed by Schafer in the subcutaneous tissue of young rats. These 

 cells are always the seat of origin of non-nucleated red blood-corpuscles, 

 which arise in the protoplasm of vaso-formative cells, as chlorophyll 

 grains or starch granules arise within the cells of plants. The 

 corpuscles escape and are washed into the circulation, when the cells 

 form connections with the circulatory system by means of their pro- 

 cesses. It is probable that the vessels so formed in the omentum are 

 only temporary. May it not be that there are many other situations 

 in the body where blood is regenerated 1 



[The observations of Schafer also prove the infra-cellular origin of 

 red blood-corpuscles, and although this mode usually ceases before 

 birth, still it is found in the rat at birth. The protoplasm of the 

 subcutaneous connective tissue-corpuscles, which are derived from the 

 mesoblast, has in it small coloured globules about the size of a 

 coloured corpuscle. The mother-cells elongate, become pointed at 

 their ends, and unite with processes from adjoining cells. The cells 

 become vacuolated ; fluid or plasma, in which the liberated corpuscles 

 float, appears in their interior, and ultimately a communication is 

 established with the general circulation.] 



Similar observations have been made by Neumann in the embryonic liver ; by 

 Wissotzky in the rabbit's amnion ; by Klein in the embryo chick ; and by Leboucq 

 and Hayem in various animals ; all of which go to show that at a certain early 



