THE BLOOD IX CHOLERA. 367 



causes might be assigned to it, and mucli miglit be said in 

 favour of each of them. It might be due only to the thickened 

 condition of the blood, which hindered it from passing through the 

 pulmonary capillaries, although they were not contracted beyond 

 their normal calibre, or the thickened blood itself may act as 

 an irritant to them and cause them to contract. It is very 

 probable that the thickened state of the blood is one cause, and 

 by no means an unimportant one, of the retarded flow of the 

 blood ; but it appears also likely that contraction of the pul- 

 monary capillaries is present in addition, and also that it does 

 not depend on the condition of the blood, for, as Niemeyer and 

 others have pointed out, the symptoms of collapse may dis- 

 appear so quickly that it can hardly be supposed that time 

 enough has elapsed to allow of the absorption of sufficient fluid 

 to restore to the blood its normal amount of water.* 



The blood in cholera has the colour of bilberry juice, and this 

 might be supposed to indicate changes in it which would cause 

 it to act as an irritant to the pulmonary vessels, and cause them to 

 contract independently of any change in the amount of water it 

 contained. This, however, can hardly be the case, as Kruken- 

 bergt has found this condition continue for weeks. This pecu- 

 liar colour of the blood is probably due to some of it having 

 become so completely deoxidised in the capillaries, that the 

 hpemogiobin has passed out of the corpuscles into the plasma, 

 and this view is confirmed by the dark red colour which the 

 serum sometimes presents {FarJces on Cholera, p. 124). When 

 blood has undergone deoxidation to such an extent that this 

 occurrence takes place, it ceases to become red when exposed to 

 air, but it nevertheless takes up oxygen and gives off carbonic 

 acid in the usual way. This fact explains the statement made 

 by Eayer, that blood in cholera does not become red when 

 exposed to air ; and the observation of Searle {Searle on Cholera, 

 p. 62), that the blood drawn from the arteries in cholera is often 

 dark coloured. 



Besides the causes already mentioned, there are two others to 

 which the contraction of the pulmonary vessels might readily be 



* Kiemeyer, SymptomatiscTie Behandlung der Cholera, p. 14. 

 t Niemeyer, <yp. cit., p, 13. 



