1909.] Method of Estimating Total Volume of Blood, etc. 



383 



If the plasma, obtained before injection, contained a small percentage of 

 dissolved haemoglobin, as usually happens in the human subject, this was 

 subtracted from that present after injection of haemoglobin solution. 



When the total amount of haemoglobin injected (C) has been determined, 

 and also the percentage of haemoglobin contained in the blood plasma after 

 injection (D), the total amount of blood plasma after injection (E) is calculated 

 from the formula 



E = x 100. 



From this the amount of fluid injected was subtracted, and to it should be 

 added the amount of plasma withdrawn, if the animal had been bled before 

 injection. By way of illustration the continuation of the experiment upon a 

 rabbit, already referred to in (1), is shown below, the amount of haemoglobin 

 (C) being expressed as before in terms of red blood cells in the moist 

 condition, the volume of red cells being given instead of their weight in order 

 to avoid calculation of the latter, and the percentage of haemoglobin (D) being 

 similarly expressed in equivalent volume of red cells. 



Amount of dissolved 

 haemoglobin injected into 

 blood stream. 



C. 



Percentage of 

 haemoglobin dissolved 

 in blood plasma 

 after injection. 

 D. 



Total volume of 

 blood plasma. 



gxlOO. 



Total volume of blood 

 [hsemocrit determination 

 gave 82*1 per cent, by 



volume of plasma 

 in undiluted blood]. 



0"74 c.c. dissolved in 0'85- 

 per-cent. NaCl solution, 

 the total volume of fluid 

 being 4rO c.c. 



- 73 per cent. 



101 c.c. after in- 



jection 

 .•. 97 c.c. before 



injection 



97 x 100-0 , , q 

 — — — — = 118 c.c. 

 821 



In no case could any change in the general condition of the rabbits be 

 observed after the injection of dissolved haemoglobin, In man the injection 

 of dissolved haemoglobin, obtained from the subject's own red cells, in amount 

 sufficient to cause the blood plasma to contain as much haemoglobin as was 

 present in 1 per cent, of its volume of red blood cells, also produced no 

 alteration of the general condition. Aseptic precautions were employed 

 throughout these procedures. 



The amount of haemoglobin can be varied within wide limits. If, however, 

 the blood plasma contains less dissolved haemoglobin than would be 

 represented by 1 per cent, of its volume of red blood cells, the natural colour 

 of the normal plasma may interfere with the haemoglobinometer determination. 

 This is likely to occur if the blood plasma before injection is unusually dark, 

 as sometimes occurs in pathological conditions attended with red cell 



