THE BLOOD. 

 By E. A. SCHAFER. 



CONTENTS : General Properties, p. 141 Amount, p. 141 Colour, p. 142 Specific 

 Gravity, p. 143 Reaction, p. 144 Coagulation, p. 145 Relative Amounts of 

 Plasma and Corpuscles, p. 147 Number of Corpuscles, p. 149 General Com- 

 position of Blood, p. 153 Composition of Blood Corpuscles, p. 155 Composi- 

 tion of Plasma, p. 156 Proteids of Plasma, p. 161 Theories of Coagulation, 

 p. 168 Causes of Coagulation, p. 178 Lymph and allied Fluids, p. 181. 



THE blood is a red fluid of alkaline reaction ; in man its specific gravity 

 is about 1*060. It has an odour which is different in different species 

 of animals, and is brought out by the addition of sulphuric acid. It 

 sets more or less rapidly into a solid clot or coagulum after death, or on 

 removal from the living blood vessels. It consists of a clear, yellowish 

 liquid, the plasma or liquor sanguinis, and of microscopic particles or 

 corpuscles of two kinds : the one kind, less numerous, termed the white, 

 or colourless, or lymph corpuscles (leucocytes) ; the other kind, by far 

 the most numerous, the red, or coloured corpuscles (erythrocytes), 

 which give the blood its characteristic tint. In addition to these, a 

 variable number of much finer discoid colourless particles (elemen- 

 tary particles, blood-platelets) are apparent in a microscopic preparation 

 of drawn blood. 



Amount. The amount of blood in the body was determined in the 

 following manner by Welcker : l A measured sample of blood is drawn, 

 and, after being defibrinated, portions of it are diluted to different degrees 

 to serve as samples of comparison. The rest of the blood is then collected 

 and defibrinated, and the vessels are washed out with salt solution until 

 the washings are colourless : they are all added to the defibrinated blood, 

 which is now diluted with water until it corresponds in tint with one of 

 the above samples, the dilution of which is accurately known. The total 

 quantity of blood in the vessels can then be calculated. In order to 

 obtain every trace of blood, Welcker further minced up the whole 

 animal and extracted the tissues with water, adding this to the mass 

 of blood. Some haemoglobin would thereby, however, be yielded by the 

 muscles (Kiihne). 



The amount has also been determined during life by the method 

 of Grehant and Quinquaud, 2 who allowed an animal to inspire a 



1 Ztschr. f. rat. Med., 1858, Ser. 3, Bd. iv. S. 147. Welcker's method is improved 

 by combining the haemoglobin with carbonic oxide gas (Gescheidlen). 



2 Compt. rend. Acad. d. sc., Paris, 1882, tome xciv. p. 1450 ; Journ. de Vanai. et 

 physioL etc., Paris, 1882, No. 6, p. 564. 



