Origin and Death of the Red Blood-Corpuscle. 303 



change in form, however, is sufficient to give rise to the beHef 

 that oxygen is the active agent in causing the biconcave shape. 



In speaking of the difference in color between arterial and 

 venous blood, Foster says (Foster's Physiology, 2d edition, page 

 277, 1878): "There may be other changes. * * * When 

 a corpuscle swells, its refractive power is diminished. * * " 

 Anything, therefore, which swells the corpuscles tends to darken 

 blood. * * * Carbonic acid has apparently some influence in 

 swelling the corpuscles." And, it might be added, it swells them 

 becauses it displaces the excess of oxygen as described above. 

 There is no such excess of oxygen in the white corpuscles, because 

 they have no haemoglobin to draw oxygen to them. Dissolve out 

 the hemoglobin or remove the excess of oxygen from the red cor- 

 puscles, and they will not be unlike the white in shape. Hence, 

 all that is necessary to change a white to a red corpuscle is the 

 dissemination of hcemoglobin through the substance of the lat- 

 ter ; this will attract an excess of oxygen, and a change in shape 

 results. 



If the corpuscles have such a short existence, the question na- 

 turally arises : Where and how do they die ? 



The serum of fresh blood contains no dissolved haemoglobin, 

 so that if any red corpuscles are destroyed in the circulation, either 

 the number must be very small, or else the haemoglobin must be 

 speedily transformed into some other body. 



Experiments made to show that the liver is a place of destruc- 

 tion for the red cells have given contradictory results. However, 

 "a careful examination of the figures leads to the conclusion that 

 the red globules are rather destroyed than formed in the liver." 

 {Physiology, Kiiss, 2d edition, page 124, 1815.) 



An account of the histology of the spleen will throw light upon 

 the matter under consideration. 



Following the divisions of the splenic artery, it is seen to divide 

 again and again, until finally the branches diminish to the size of 

 capillaries. These soon become indistinct. Cell demarcations 

 may still be recognized, but these also soon disappear, and there 

 is now a minute blood current without definite walls. (Frey's 

 Camp, of Histology, '^■s.^t 120, 1876.) " As the failing branch of 

 a drying brook wanders at last between the pebbles of its bed, 

 slender and scanty, so is it with these finest blood-currents." 



The blood now enters the splenic artery and flows undisturbed 

 through the branches to the very finest capillaries. The walls 



