BIOLOGY. 



[BOOK i. 



other, and every one of which seems to be an isolated cell. A 

 more attentive examination soon shows that these bodies are 

 rather glomerules than real cells, for they have neither nuclei 

 nor enveloping membranes. They are small flattened disks, 

 depressed in the centre on their two faces, an arrangement which 

 often simulates a nucleus. Their diameter is from O mm , 006 to 

 O mm , 907, in the adult man. But their form varies in the series 

 of the vertebrates, and also in man and the mammifers if we 

 remount to the first stage of the embryological life. In effect, 

 at the epoch when the embryon has only a length of O m , 02 to 

 O m , 03, where the globules begin to appear, they are white, and 

 have a veritable nucleus. According to some authors they then 

 multiply by segmentation. They are now much longer, and their 

 diameter attains O mm , 010, to O mm , Oil. 



In the animal series we also observe very notable differences 

 in the form, the volume, and the struc- 

 ture of the sanguineous globules. As 

 long as we are simply considering the 

 class of the mammifers, these differences 

 are slight. However, the sanguineous 

 globules of the camel and of the llama 

 have an ovalar ellipsoidal form, and re- 

 semble those of birds and reptiles. In 

 the elephant and in the didactylus sloth 

 we also find sanguineous globules much 

 longer than in the other mammifers. 



In the other classes of vertebrates the 

 differences grow more striking. In all 

 the vertebrates the globules are, as in 

 Frog.- a and 6 front view and' man, of a red colour by reflection, and 



profile of a red globule ; c, . , . , , , , , , TIT 



white globule, 500 diameters, it IS to them that the blood OW6S its 

 Man. d and e, front view and ,.-, ,. , T -, ,-, 111 



profile of a sanguineous gio- rutilant tint. In general the red glob- 



of the mammifers are less volu- 



of the chyle, 800 diameters. minous than those Q f the other clasges Q f 



vertebrates. They are elliptical and nucleated in the classes of 



