14 (i PHYSIOLOGY CHAP. 



environment. A mechanical explanation of the greater resist- 

 ance of nucleated erythrocytes to the diffusion of their haemo- 

 globin, even in very dilute solutions of sodium chloride, may, 

 according to these authors, consist in the fact either that the 

 nucleus of the cell exerts a positive cheniotactic influence on 

 the haemoglobin of the strorna, or that the haemoglobin makes 

 a more stable combination with the lecithin of the stroma. 

 In any case, it is clear from these results that the resistance of 

 the nucleated corpuscles is neither an expression nor a measure 

 of intracorpuscular osmotic pressure. 



In a series of publications (1895-97) Manca (experimenting 

 always with the red blood-corpuscles of mammalia, i.e. with non- 

 nucleated erythrocytes) sought to determine the relations in these 

 between vitality and osmotic pressure, in order to distinguish the 

 physiological from the purely physical factors in the pheno- 

 mena of their resistance and osmotic exchanges with the plasma. 

 He set 'out from the conclusions of Hamburger, Limbeck, and 

 other physiologists and pathologists, who, in considering the varia- 

 tions of resistance offered by the erythrocytes to various physio- 

 logical and pathological conditions, interpret these phenomena as 

 dependent on changes in their vital conditions, and affirm that 

 only living erythrocytes obey the laws of osmosis and of isotouic 

 coefficients. The problem, attacked by Manca from various aspects, 

 led to a consensus of results, which may be summarised in a few 

 words. 



In experiments made with the venous blood of dogs, both 

 before and after prolonged muscular exertion, he found that the 

 resistance of the erythrocytes (determined by Hamburger's method) 

 underwent a slight but constant increase. 



Erythrocytes treated in ritro with strong doses of cocaine 

 hydrochlorate, strychnine sulphate, atropine sulphate, morphine 

 hydrochlorate, showed less resistance than the normal, but 

 perfectly obeyed the same laws that govern the osmotic exchanges 

 of normal blood-corpuscles. 



The resistance of the corpuscles left to themselves outside the 

 body, with no aseptic precautions, also diminishes gradually ; but 

 after 3-10 days (when, according to Hamburger, they must be 

 considered as dead) they react to solutions of NaCl and KC1 like 

 normal erythrocytes, and obey the same laws of osmosis. The 

 erythrocytes behave towards dilute solutions of the same salts in 

 such a way that it must be assumed that the molecules of NaCl 

 and KC1 are equally dissociated or ionised, and that the erythrocytes 

 are either impermeable to them or permeable to the same small 

 extent. 



The erythrocytes of the blood when treated in vitro with even 

 the strongest doses of chloroform, and those from the blood of 

 animals killed with chloroform, show a lower resistance than the 



