2 44 TEXT-BOOK OF PHYSIOLOGY. 



during a menstrual period 150 c.c. of blood. At the end of twenty- 

 eight or thirty days this volume is restored, so that in one day 5 c.c., 

 or 5000 c.mm., of blood must be formed, or 208 c.mm. per hour and 

 3J c.mm. per minute. \That is, during a certain number of years 

 15,750,000 corpuscles must be formed every minute, and this inde- 

 pendent of the daily loss due to functional activity^ 

 \At the present time there is a general agreement among histolo- 

 gists that in adult life the red corpuscles are derived from embryonic 

 forms, the so-called erythroglasts, which are tound cTJIefly in the 

 marrow of the long bone's/^' In this situation both arterial and venous 

 capillaries arc relatively large and the blood is separated from the 

 surrounding marrow by extremely thin walls.^ In the passages of this 

 capillary network the erythroblasts make their appearance most 

 probably by a transformation of preexisting marrow cellsS^At first 

 they are large, homogeneous, colorless, perhaps slightly tinged with 

 hemoglobin and distinctly nucleated. yThey increase in number by 

 karyokinesis and at the same time increase in their hemoglobin con- 

 tent. > ^he_nukujsfinaJUy - fi2da^ carrying with it a portion of 

 the perinuclear cytoplasm, after which the remainder of the cor- 

 puscle assumes the shape and size of the adult corpuscle and is carried 

 out into the general circulation. After severe hemorrhage the forma- 

 tive processes in the marrow may become so active that erythroblasts 

 make their appearance in the blood-stream before the extrusion of 

 the nucleus has taken place. 



CHEMIC COMPOSITION OF RED CORPUSCLES. 



Hemoglobin. The red^corpuscle consists of a stroma and a 

 coloring-matter, hemoglobin. In the normal condition the latter is 

 amorphous and in some"~unknown way combined with the former 

 and not merely diffused in its meshes. 1 ^ The amount of hemoglobin 

 per corpuscle is estimated at pp per cent^y so that the corpuscle may 

 be conceived of as a mass of hemoglobin supported and enclosed by a 

 protoplasmic stroma. 



If blood which has been rendered laky, by water or any other 

 of the known agencies, be allowed to slowly evaporate, the dissolved 

 hemoglobin undergoes crystallization. The rapidity with which the 

 crystals form varies in the blood of different animals under similar 

 conditions. According to the ease with which crystallization takes 

 place, Preyer has classified various animals as follows: (i) Very 

 difficult calf, pigeon, pig, frog; (2) difficult man, monkey, rab- 



* For an admirable resume of the various views regarding the origin and formation 

 of red corpuscles see the paper of Mr. Charles L. Mix, Boston Med. and Surg. Journal, 

 1892, Nos. ii and 12; also paper by Prof. W. H. Howell, Journal of Morphologv, 



