136 SANGUIFICATION. LECT. VII. 



would have equally coagulated; but in doing so it would 

 have enclosed in its mass the suspended globular matter, 

 as happens with blood out of the living body. According 

 to circumstances which are altogether physical, such as the 

 temperature of the blood drawn, the density of the serum, 

 and the different proportions of globules and fibrine, co- 

 agulation takes place more or less quickly, is more or 

 less abundant, arid the coagulum formed offers a greater or 

 less resistance. 



rfrterialization of the Blood. If we take the clot formed 

 in blood left to itself, and treat it with oxygen, we observe 

 that it acquires a vermilion colour. This clot, left in the 

 air, and then cut, is blackish internally, but red externally. 

 The fresh surfaces formed by the incision, soon become red 

 by exposure to the air. It is undoubtedly the globules of 

 the blood which undergo this change of colour by contact 

 with air. 



Baudrimont and Martin Saint-Ange have recently shown 

 that at the period of incubation, an absorption of oxygen 

 and exhalation of carbonic acid take place through the 

 calcareous envelope of the egg; and they have proved, that 

 if these phenomena be prevented, the small red globules 

 do not appear in the embryo, which does not become de- 

 veloped. 



M. Dumas has shown that the globules of the blood 

 remain unaffected, and without dissolving, if we carefully 

 expose them to the contact of atmospheric air continually 

 renewed. 



It yet remains to be ascertained whether these globules 

 become red solely by the oxygen which they absorb, or by 

 the loss of carbonic acid which they suffer during respira- 

 tion ; or if, on the contrary, the blood becomes venous in 

 consequence of the larger quantity of carbonic acid with 

 which it is charged, or on account of the smaller quantity 



