IN DISEASES. 265 



that the blood exhibits a perfectly identical or even an analogous 

 composition in all conditions included under this designation, since 

 the composition of the blood must necessarily correspond with 

 the morbid process which preceded the diminution of the blood ; 

 for the properties which have commonly been ascribed to anaemic 

 blood belong, properly speaking, to a hydraemic condition. We 

 must, at all events, presume that the blood in anaemia depending 

 upon excessive haemorrhage, differs in composition from that exhi- 

 bited in the anaemia which arises from large tumours, excessive 

 mental labour, bad food, poisoning, &c. Experience teaches us, 

 moreover, that the anaemia which follows carcinoma, typhus, haemor- 

 rhages, and other losses of the juices, may easily pass into hydraemia, 

 whilst in tuberculosis a hydrsernic state of the blood is scarcely 

 ever found to occur together with the corresponding serous exuda- 

 tions. Anaemic blood does not therefore indicate the existence of 

 any special admixture of the blood. It is only in respect to the 

 diminution of the coloured blood-cells that the composition of 

 this blood corresponds with that exhibited in hydraemic and 

 chlorotic conditions. 



In chlorosis the blood forms a small solid clot covered with a 

 bufty coat, and floating in a large quantity of clear serum. The 

 corpuscles and the iron are both diminished either in a very small 

 or in an excessive degree, without, however, standing in any 

 definite relation to the intensity of the disease. The quantity of 

 fibrin does not greatly exceed the normal average ; the quantity of 

 albumen is only increased relatively to the blood-cells, while the 

 fats and salts remain entirely normal. 



In the so-called plethora, the blood-corpuscles are always some- 

 what more numerous ; the serum and the fibrin are both nearly 

 normal, and the albumen of the liquor sanguinis rises only slightly 

 above the mean average. Plethora seems to bear the same 

 relation to spinal irritation as anaemia does to chronic spinal 

 affections, the only difference being a greater increase of the solid 

 constituents, and more especially of the blood-corpuscles, in the 

 former. 



The blood experiences no changes in typhus, which can justify 

 us in terming this disease a dyscrasia. From the 5th to the 8th 

 clay, and therefore nearly as long as the continuance of the 

 typhous exanthema, we find that the composition of the blood 

 bears a great similarity to that exhibited in plethora, for the cor- 

 puscles are increased, as also are the solid constituents of the serum, 

 and especially the albumen ; even the fibrin is generally aug- 



