DEVELOPMENT OF THE BED BLOOD-CORPUSCLES 91 



the "ghost." After the addition of water the white corpuscles 

 become' spherical ; their granules display the dancing " Brownian 

 motion; " they swell, and finally burst. Weak acetic acid decolorizes 

 the red corpuscles, and clears the granules of the white corpuscles 

 so that their nuclei become visible. Weak solutions of tannic acid 

 coagulate the coloring matter of the red corpuscles, which escapes 

 from the cell, clinging as a minute particle to one edge. 



DEVELOPMENT OF THE RED BLOOD -CORPUSCLES 



The red blood -corpuscles of the mammalian embryo possess 

 nuclei, and in this respect resemble those of birds, reptiles, amphib- 

 ians, and fishes.* 



The nucleated red corpuscles of the mammalian embryo and of 

 the young forms of the lower vertebrates multiply by karyokinesis. 

 At birth, however, in mammals the nucleated corpuscles are found 

 to have been replaced by the ordinary, non- nucleated, discoidal 

 forms. The origin of the non -nucleated corpuscles and the man- 

 ner of their renewal throughout life are uncertain. It has been- 

 suggested that they are developed from leucocytes and also from 

 the blood -plates, but both of these theories lack confirmation. It 

 seems probable that the nucleated cells colored with haemoglobin, 

 found in the red marrow of the bones, are the most important 

 source of the red corpuscles. According to Ho well, the nucleated 

 red corpuscles of the marrow lose their nuclei by extruding 

 them. 



*The red blood-corpuscles of the order of fishes known as Cyclostomi, of which the lamprey 

 is a member, are circular, nucleated disks. Amphioxus has no red blood-corpuscles. 



