RED BLOOD-CORPUSCLES. 265 



liquids. In the discharged blood they may sometimes lie with their 

 flat surfaces together, forming a cylinder like a roll of coin (rouleaux). 

 The reason for the phenomenon, which is considered as an agglutination, 

 has not been sufficiently studied, but as it may be observed in defibrinated 

 blood it seems probable that the formation of fibrin hac nothing to do 

 with it. 



The number of red blood-corpuscles is different in the blood of various 

 animals. In the blood of man there are generally 5 million red corpuscles 

 in 1 c.mm., and in woman 4 to 4.5 million. 



The blood-corpuscles consist essentially of two chief constituents, 

 the stroma, which forms the real protoplasm, and the intraglobular 

 contents, whose chief constituent is hemoglobin. We cannot state 

 anything positive for the present in regard to a more detailed arrange- 

 ment, and the views on this subject are somewhat divergent. The two 

 following views are more or less related to each other. According to one 

 view the blood-corpuscles consist of a membrane which encloses a haemo- 

 globin solution, while the other view considers the stroma as a proto- 

 plasmic structure soaked with haemoglobin. This latter view is in accord 

 with the assumption as to an outside boundary-layer. 



Thus according to HAMBURGER the stroma forms a protoplasmic 

 net in whose meshes there exists a red fluid or semi-fluid mass which 

 consists in great measure of hemoglobin. This mass represents the 

 water-attracting force of the blood-corpuscles, and besides this it is also 

 considered that the outer protoplasmic boundary is semi-permeable, 

 i.e., permeable to w r ater but not permeable to certain crystalloids. The 

 researches of KOPPE, ALBRECHT, PASCUCCI, Rywoscn, 1 and others 

 indicate the presence of a special envelope or boundary-layer, and there 

 is no doubt that the outer layer contains so-called lipoids, such as choles- 

 terin, lecithin, and similar bodies. 



The red blood-corpuscles retain their volume in a salt solution which 

 has the same osmotic pressure as the serum of the same blood, although 

 they may change their form in such solutions, becoming more spherical, 

 and may also undergo a chemical change. Such a salt solution is isotonic 

 with the blood-serum, and its concentration for a NaCl solution is 

 approximately 9 p. m. for human and mammalian blood. A solution 

 of greater concentration, a hyperisotonic solution, abstracts water from 

 the blood-corpuscles until osmotic equilibrium is established, hence the 

 corpuscles shrink and their volumes become smaller. In solutions of 

 less concentration, hypisotonic solutions, the corpuscles swell up, due to 

 the taking up of water, and this swelling may. be so great, as on diluting 



1 See Hamburger, Osmotischer Druck und lonenlehre, 1902; Koppe, Pfliiger's 

 Arch., 99 and 107; Albrecht, Centralbl. f. Physiol., 19; Pascucci, Hofmeister's Beitrage, 

 6; Rywosch, Centralbl. f. Physiol., 19. 



