82 INTRODUCTION. 



ed by washing it, is always a mixture of the free red matter of 

 the globules enveloped in the same matter, and of serum. We 

 consequently find, that the most able chemists, have as yet, 

 learned but little respecting Jhe colouring matter of the blood, 

 or the zoohematine. This substance, insoluble in water, but 

 capable of an extraordinary division in it, so as to pass through 

 the filter, is composed of an animal matter in combination with 

 the peroxide of iron. The red colour of the blood has different 

 shades. 



77. The fibrine of the blood, or the coagulable lymph of 

 some authors, resembles tenacious elastic downy fibres, pre- 

 senting under the microscope the aspect of the muscular fibre, 

 being composed of white globules similar to those of the co- 

 loured particles of the blood; the fibYine also, like the muscular 

 fibre, being placed in water, resolves itself into globules pre- 

 vious to putrefaction. This coagulable or plastic substance, 

 as well as albumen, appears to be the medium of agglutination 

 which occasions the reunion and adherence of divided parts 

 of the body. 



The blood contains also a fatty or oily matter. 



78. The blood contained in the arteries, veins, and heart, 

 is constantly in motion; this is called the circulation. During 

 this movement, it undergoes constant and regular changes, 

 which, being exactly balanced, preserve it in a medium state of 

 composition. It receives new liquids, prepared by digestion 

 and intestinal absorption; molecules separated from the organs, 

 are unceasingly added to its mass; it is submitted to the action 

 of the atmosphere in the lungs, where it is revivified; it is then 

 sent to all parts of the body, where it undergoes an inverse al- 

 teration, where it furnishes materials that fix themselves in the 

 organs, and where it is deprived of a part of its principles by 

 the secretions. Amid all these changes, none are so striking 

 as those it undergoes in the lungs, where it becomes of a bright 

 red or vermillion, and in the remainder of the body where it 

 assumes a reddish brown colour. These alterations of colour, 

 appear to depend, in the first case, upon an absorption of oxy- 

 gen, and in the second, of carbone. Besides, the nutritive 



