PATHOLOGICAL CHANGES IN THE BLOOD. 447 



proportions of the Organic elements of the fluid. It is of course necessary to 

 determine, in the first instance, what are the usual or normal proportions ; 

 and the following is estimated by them, from numerous analyses, as the ordi- 

 nary quantity* of each element in 1000 parts of healthy blood. 



Fibrin 3 



Globules 127 



Solid matter of serum 80 



Water 790 



The proportion of Fibrin may vary, within the limits of health, from 2 to 3, 

 or even from 2 to 4: but these last extremes are rarely met with in perfect 

 health ; and must be considered, when they occur, as exceptions dependent 

 on idiosyncrasy. The extremes in the proportion of Globules, in the physio- 

 logical condition of the system, are fixed at 110 and 140; the latter converging 

 towards the condition of the blood characteristic of Plethora. 



591. The inquiries which have been made by Andral, in regard to the 

 alterations which these proportions undergo in various states of Disease, have 

 already led to results of great interest and value ; and there can be no doubt 

 that these will be greatly extended, when this simple analytical process shall 

 have been more generally employed. As an instance of the erroneous conclu- 

 sions into which we may be led, by merely attending to the size of the crassa- 

 rnentum, it may be remarked that the existence of a large Clot does not by 

 any means necessarily imply the presence of an increased amount of Fibrin ; 

 since it may depend upon the retention within it of a large proportion of 

 Serum, consequent upon the deficient contractile power of the clot, which 

 results from a diminution in the proportion of Fibrin. When the clot is dense 

 and contains but little Serum, it may be judged to contain a full proportion of 

 Fibrin, even though it may itself be small. Before entering upon the con- 

 sideration of the alterations in the Blood which are affected by particular mor- 

 bid states, Andral notices two extraneous causes, usually operating in disease, 

 which may affect the result. These are, abstinence from food, and loss of 

 blood by venesection. It has been commonly stated, that they have a tendency 

 to diminish the proportion of all the solid elements of the blood; but this is not 

 the case ; for they seem especially to act upon the Globules, the quantity of 

 Fibrin remaining nearly the same, unless the hemorrhage have been very 



* The analysis of the Blood with reference to the quantity of the chief proximate ele- 

 ments which it may contain, is very easily 'accomplished; and as the determination of 

 this is the point of most practical importance, the method adopted in the inquiries of 

 MM. Andral and Gavarret will be here detailed. The blood is caused to flow into two 

 different vessels; into one vessel, the first and last quarters of the blood are received; 

 and into the other, the second and third quarters: in this manner, the similarity of the 

 two quantities is secured as far as possible. The blood in one vessel is allowed to coag- 

 ulate spontaneously; that in the other is beaten with a small rod, in order to separate the 

 fibrin. When the first portion is completely coagulated, the serum is carefully separated 

 from the crassamentum; and there are then dried and weighed, 1. The Fibrin obtained 

 by the rod; 2. The whole Crassamentum; 3. The Serum. The weight of the sepa- 

 rated fibrin gives us the quantity of it contained in the clot. The weight of the serum 

 after complete desiccation, gives us the proportional quantity of solid matter contained 

 in its water. The quantity of water driven off" from the clot in. drying, gives us the 

 amount of serum it contained; from which may be estimated the proportion of the solid 

 matter of the serum that the crassamentum included. Hence, by deducting from the 

 weight of the whole dried clot, first, that of the fibrin separated by agitation, and then that 

 of the solid elements of the serum, ascertained by calculation, we obtain the weight of 

 the globules. In order to ascertain the whole amount of solid matter in the serum, that 

 which was ascertained by calculation to exist in the fibrin, is added to that which was 

 obtained from the separate serum. The proportion of organic and of inorganic matter in, 

 this solid residuum, is ascertained by incinerating it in a crucible; by which the whole 

 of the former will be driven off, and the latter will be left. 



