74 ANALYSIS OF THE BLOOD. 



remain at rest, you have found it separated into three 

 very distinct portions, viz. the serum, a thin, watery fluid ; 

 the fibrine, a thick, tenacious, jelly-like mass floating on 

 the surface of the serum ; and a quantity of red globules 

 which adhere to the under surface of the mass of fibrine. 



Emily. I recollect having observed some blood a 

 short time after it was drawn, and was surprised to find 

 that it had completely lost its fine dark red tint, and be- 

 came almost colorless. I suppose that if I had raised 

 the cake of fibrine, I should have found the red parts, 

 which had so mysterously disappeared. But what is 

 the composition of these different portions ? 



Dr. B. The constituent prinicples of the serum, are 

 water, albumen and a small quantity of soda ; those of 

 the fibrine, we fibrine, a peculiar animal substance, and 

 a small portion of a few saline and animal substances ; 

 the red portion of the blood is thought to resemble fibrine 

 and contains also, iron and sulphur, in very small quan- 

 tities. 



Emily.- This is wonderful indeed. I cannot imag- 

 ine in what manner iron and sulphur can get into the 

 blood, for we certainly take neither of these substances 

 with our food. 



Dr. B. It is so difficult to account for their uniform 

 appearance, that it has been supposed the iron was form- 

 ed in the process of analysis. Their aggregate quantity 

 in an individual has never been determined with much 

 accuracy. By one or two experiments it has been es- 

 timated at three ounces, the whole quantity of blood be- 

 ing abont twenty four pounds. Another curious fact in 

 regard to the blood, is that it is composed of minute glob- 

 ules similar to those which form the elementary tissues. 



J2mily. Is the blood of the inferior animals like that 

 of man ? 



Dr. B. Chemical analysis detects no difference, 

 though some difference no doubt, exists. It has been 

 found that a dog may be bled till all sensible manifesta- 

 tions of life have disappeared, and restored immediately 



