12 ORIGIN OF THE RED BLOOD-CORPUSCLES. 



this country by Gulliver, but the relative size may be best appreciated 

 by comparing the corpuscles from various vertebrates.] 



Many invertebrates possess red, violet, brown, or green opalescent blood with 

 colourless corpuscles (amoeboid cells). In cephalopods, and some crabs, the blood 

 is blue, owing to the presence of a colouring-matter (Hcemo-cyanln) which, con- 

 tains copper, and combines with O (Bert, Kabuteau & Papillon, Fre"dericq, and 

 Krukeuberg). The large blood-corpuscles of many amphibia, e.g., amphiuma, are 

 visible to the naked eye. The blood-corpuscles of the frog contain, in addition to 

 a nucleus, a micleolus (Auerbach, Ranvier), [and the same is true of the coloured 

 corpuscles of the newt (Stirling). The nucleolus is revealed by acting on the 

 corpuscles with dilute alcohol (1, alcohol; 2, water; Ranvier's "a!cool au tiers").'} 

 It is evident that the larger the blood-corpuscles are, the smaller must be the number 

 and total superficies of corpuscles in a given volume of blood. In birds, how- 

 ever, the number is relatively larger than in other classes of vertebrates, notwith- 

 standing the larger size of their corpuscles ; this, doubtless, has a relation to the 

 very energetic metabolism that takes place in birds (Malassez). 



Amongst mammals, caruivora have more blood-corpuscles than herbivora. 

 Welcker has ascertained that goat's blood contains 9,720,000 corpuscles per cubic 

 millimetre; the llama's, 13,000,000; the bullfinch's, 3,600,000; the lizard's, 

 1,420,000; the frog's, 404,000; the proteus', 36,000. In liybernatinrj animals, 

 Vierordt found that the number of corpuscles diminished from 7,000,000 to 

 2,000,000 per cubic millimetre during hybernation. 



7. Origin of the Red Blood-Corpuscles. 



(A.) Origin of the Nucleated Red Corpuscles during Embryonic 

 Life. Blood-corpuscles are developed in the fowl during the first days 

 of embryonic life. [They appear in groups within the large branched 

 cells of the mesoblast, in the vascular area of the blastoderm outside 

 the developing body of the chick or embyro, where they form the 

 " Hood-islands " of Pander. The mother-cells form an irregular net- 

 work by the union of the processes of adjoining cells, and meantime 

 the central masses split up, and the nuclei multiply. The small 

 nucleated masses of protoplasm, which represent the blood-corpuscles, 

 acquire a reddish hue, while the surrounding protoplasm, and also that 

 of the processes, becomes vacuolated or hollowed out, constituting a 

 branching system of canals ; the outer part of the cells remaining with 

 their nuclei to form the walls of the future blood-vessels. A fluid 

 appears within this system of branched canals in which the corpuscles 

 lie, and gradually a communication is established with the blood- 

 vessels developed in connection with the heart.] 



[According to Klein, the nuclei of the protoplasmic wall may also 

 proliferate, and give rise to new corpuscles, which are washed away to 

 form blood-corpuscles.] At first the corpuscles are devoid of pigment, 

 nucleated, globular, larger and more irregular than the permanent 

 corpuscles, and they also exhibit amoeboid movements. They become 



