6 OP THE BLOOD. 



mixed, and form an equable, homogeneous fluid. Their 

 relative proportion is astonishingly diversified, accord- 

 ing to age, temperament, diet, and similar circum- 

 stances which constitute the peculiar health of each 

 individual. 



11. The serum is a peculiar fluid, the chief cause of 

 the viscidity of the blood, and easily separable by art 

 into different constituent principles. If subjected to a 

 temperature of 150° Fahr. a portion is converted into a 

 white scissile substance, resembling boiled albumen: 

 the rest exhibits, besides the watery fluid so often men- 

 tioned, a turbid fluid of a gelatinous, or rather mucous,* 

 nature, which on cooling appears a tremulous coagu- 

 lum. The serum is remarkable for the quantity of soda 

 (mineral alkali) which it contains. (E) 



12. The cruor has many peculiarities, in regard to 

 both the colour and the figure of its particles. It con- 

 sists of globules, which in recent blood are of a constant 

 form and size, and said to be ?-&-$ of an inch in dia- 

 meter. Their form, indeed, has been a subject of dis- 

 pute ; but I am disposed to consider it as much more 

 simple than some writers of great celebrity have ima- 

 gined. I have always found it globular, and could 

 never discover the lenticular shape which some have 

 asserted that they remarked. 



It has been likewise advanced, that the globules 

 change their form, while passing through a vessel of 

 very small capacity — that, from being spherical, they 

 become oval; and, when they have emerged into a 



• J. Bostock, Medico-Chirurgical Transaction*, published by the Medical 

 and Chimrgical Society of London, vol. i. 1809. p. 46. 



