12 



THE BLOOD. 



are the parts most immediately necessary to life. It is well known that life 

 may be restored to an animal in which the functions have been suspended 

 by haemorrhage, by the introduction of fresh blood ; and while it is not neces- 

 sary that this blood should contain the fibrin-factors, it has been shown by 

 the experiments of Prevost and Dumas and others, that the introduction of 

 serum, without the corpuscles, has no permanent restorative effect. When all 

 the arteries leading to a part are tied, the tissues lose their properties of 

 contractility, sensibility etc., which may be restored, however, by supplying 

 it again with blood. It will be seen, in treating of respiration, that one great 

 distinction between the corpuscular and fluid elements of the blood is the 

 great capacity which the former have for absorbing gases. Direct observa- 

 tions have shown that blood will absorb ten to thirteen times as much oxygen 

 as an equal bulk of water ; and this is dependent almost entirely on the pres- 

 ence of the red corpuscles. As all the tissues are constantly absorbing 

 oxygen and giving off carbon dioxide, a very important office of the corpus- 

 cles is to carry oxygen to all parts of the body. In the present state of 

 knowledge, this is the only well defined use which can be attributed to the 

 red corpuscles, and it undoubtedly is the principal one. They have an affin- 

 ity, though not so great, for carbon dioxide which, after the blood has cir- 

 culated in the capillaries of the system, takes the place of the oxygen. In a 

 series of experiments on the effects of haemorrhage and the seat of the " sense 

 of want of air," it was demonstrated that one of the results of removal of 

 blood from the system was a condition of asphyxia, dependent upon the 

 absence of these respiratory elements (Flint, 1861). 



Leucocytes, or White Corpuscles of the Blood. In addition to the red cor- 

 puscles of the blood, this fluid always contains a number of colorless bodies, 



globular in form, in the substance 

 of which are embedded a greater or 

 less number of minute granules, 

 forming a nucleus of irregular shape. 

 These have been called by Robin, 

 leucocytes. This name seems more 

 appropriate than that of white or 

 colorless blood-corpuscles, inasmuch 



as these bodies are not peculiar to 

 the blood, but are found in the 

 lymph, chyle, pus and various other 

 fluids, in which they were formerly 

 known by different "names. The 

 description which will be given of 

 the white corpuscles of the blood, 



FIG. 6. Human leucocytes, showing amoeboid move- and the effects of reagents, will an- 

 ments (Landois). 



swer, in the main, for all the cor- 

 puscular bodies that are grouped together under the name of leucocytes. 



Leucocytes are normally found in the blood, lymph, chyle, semen, colos- 

 trum and vitreous humor. Pathologically, they are found in the secretion 



