THE BLOOD. 
By E. A. Schafee. 
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 TOGO. 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: 1 — 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 (rrehaiit 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 Corrupt, rend. Acad. d. sc, Paris, 1882, tome xciv. p. 1450 ; Journ. de 1'aaat. et 
physiol. etc., Paris, 18S2, Xo. 6, p. 564. 
