CHAP. III.] THE BLOOD IN DISEASE. 139 



SECT. 1. Variations in the proportion of the principal Constituents of 

 the Blood in Diseases in general. 



Water I. Before considering the changes which the blood 



undergoes in different diseases, it is well to insist upon 

 the fact that loss of blood very rapidly influences the composition of that 

 which remains in the vascular system. It has been shewn by the con- 

 cordant results of many trustworthy observers 1 that when an animal is 

 bled, the portion of blood first obtained contains the largest quantity of 

 solid matter, and that this gradually diminishes, so that the blood obtained 

 at the commencement of a venesection has a slightly, but still perceptibly, 

 different composition from that obtained at its termination, unless, of 

 course, the total quantity of blood withdrawn be excessively small. 



This diminution in the solid matter of the blood which is noticeable 

 even in the course of venesection is naturally much more perceptible in 

 cases of excessive and repeated accidental haemorrhages. The diminution 

 of solid matter is partly due to actual loss of solids, but in great part to 

 the blood becoming more rapidly diluted by lymph than in the normal 

 condition. 



The normal quantity of water in the blood of man may be estimated 

 as varying between 780 and 800 parts per 1000 of blood. An increase 

 in the water of the blood is much more frequent than the converse ; this 

 increase may be only slight or it may be considerable. 



A slight augmentation of the water of the blood, i. e. to between 800 and 

 820 parts per 1000, occurs as a result of a temporary abstinence from food, 

 in the early stages of nearly all acute diseases, and in the majority of 

 chronic diseases. 



A more marked augmentation, the water amounting to between 820 

 and 880 parts per 1000 of blood, occurs in starvation: after considerable 

 haemorrhages ; in cases of abundant suppuration, or in which some other 

 considerable drain is taking place, as in chronic diarrhoea ; in the course 

 of malarial diseases ; in lead poisoning ; in chronic mercurial poisoning ; 

 in cancerous and tubercular affections : and we might add in anaemia, 

 if it were not more correct to characterize the latter as the condition which 

 really exists in all the morbid states just enumerated. 



A decrease in the quantity of water of the blood has been observed in 

 articular rheumatism, in erysipelas, in puerperal fever, and especially in 

 cholera. 



Coloured II. The coloured corpuscles are increased in the first 



Corpuscles stages of cholera ; the increase is however riot an absolute 



and Haemo- O ne, but merely dependent on a diminution of the water 

 globin. t j ie blood. A diminution of the coloured corpuscles occurs 



in the various forms of anaemia, including chlorosis ; in Bright's disease ; 

 as a result of prolonged diarrhoea and dysentery ; of continued and abundant 

 suppurative discharges; in scurvy; in leucocy thaemia ; in the advanced 

 stages of continued and of intermittent fevers; in chronic metallic poisoning ; 

 in cases of advanced heart disease; in chronic diseases generally. 



1 Pre'vost and Dumas, Becquerel and Eoclier, Simon, and others. 



