CH. XX VI.] 



DEVELOPMENT OF BLOOD-CORPUSCLES 



427 



from the rest of the cell and forms a red corpuscle, being at first cup- 

 shaped, but soon taking on the normal appearance of the mature cor- 

 puscle. Mingled with the amoeboid colourless marrow cells (p. 55) are a 

 number of other smaller amoeboid 

 cells called erythroblasts (fig. 361); 

 these are tinted with haemoglobin ; 

 they divide and multiply, lose their 

 nucleus, and are thus transformed 

 into discoid blood-corpuscles. 



From the tissue of the spleen. 

 It is probable that coloured as well 

 as colourless corpuscles may be 

 produced in the spleen from cells 

 similar to the erythroblasts of red 

 marrow. 



The belief which formerly pre- 

 vailed that the red corpuscles are 

 derived from the white or from the 

 platelets has now been discarded. 



During foetal life, and possibly 



in some animals, e.g. the rat, which Flo< 36 o._ Further development of blood- 

 are born in an immature condition, 

 for some little time after birth, the 

 blood discs have been stated by 

 Schafer to arise in the connective 

 tissue cells in the following way. 

 Small globules, of varying size, of 

 colouring matter arise in the pro- 

 toplasm of the cells (fig. 359), 

 and the cells themselves become 

 branched, their branches joining 



the branches of similar cells. The cells next become vacuolated, and 

 the red globules are free in a cavity filled with fluid (fig. 360) ; by the 

 extension of the cavity of the cells into their processes anastomosing 

 vessels are produced, which ultimately join with the previously 



cor- 

 puscles in connective tissue cells and trans- 

 formation of the latter into capillary- 

 blood-vessels, o, an elongated cell with a 

 cavity in the protoplasm occupied by fluid 

 and by blood-corpuscles which are still 

 globular; b, a hollow cell, the nucleus of 

 which has multiplied. The new nuclei are 

 arranged around the wall of the cavity, the 

 corpuscles in which have now become dis- 

 coid ; c, shows the mode of union of a 

 " hsemapoietic " cell, which, in this instance, 

 contains only one corpuscle, with the pro- 

 longation (bl) of a previously existing vessel ; 

 a and c, from the new-born rat : b, from the 

 foetal sheep. (E. A. Schafer.) 



Fio. 361. Coloured nucleated corpuscles, from the red marrow of the guinea-pig. 

 (B. A. Schafer.) 



existing vessels, and the globules, now having the size and appearance 

 of the ordinary red corpuscles, are passed into the general circulation. 

 This method of formation is called intracellular. Without doubt, the 

 red corpuscles have, like all other parts of the organism, a tolerably 



