OF THE BLOOD. 11 



vacuo, though less rapidly and deeply than if exposed to hydrogen 

 gas. Arterial blood left in contact with oxygen gradually acquires 

 the same dark colour, and no oxygen will afterwards render it 

 scarlet. Berzelius finds the colouring particles only concerned in 

 these changes, and, after all, no difference of composition can be 

 detected between scarlet and purple blood. 



It has been generally supposed that iron exists in the red par- 

 ticles of the blood as a subphosphate. Berzelius informs us that 

 serum, although able to dissolve a small portion of the oxids, 

 not indeed of the phosphates, of iron, does not acquire a red 

 colour by their addition, and that he has never discovered iron nor 

 lime in the entire blood, although both are so abundant in its 

 ashes. He concludes that the blood contains the dements of 

 phosphate of iron and of lime, and of carbonate of lime, and also 

 of phosphate of magnesia, united in a manner different from, their 

 combination in the salts. 



Mr. Bauer, whose microscopic skill is effecting so much for 

 anatomy and physiology, finds that the globules consist of a 

 colourless nucleus and an enveloping coloured portion,* as Dr. 

 Young first discovered, f A nucleus is about 3-oW ^ an mc ^ "". 

 diameter, and the whole globule nearly one-fourth larger. In the 

 unpublished paper above quoted, it is further stated that Mr. Bauer 

 has discovered a third set of smaller colourless globules in the 

 blood, ^Vo- of an inch in diameter. They appear to belong to 

 the fibrine, and Sir Everard Home accordingly denominates them 

 lymph globules. Colourless globules gradually form also in se- 

 rum. | Oxygen and hydrogen also exist in fibrine. 



(G) The fibrine, albumen, and colouring matter, afford, on de- 

 composition, the same saline and gaseous products. Berzelms 

 views them all three as modifications of the same substance. 

 Albumen contains a greater proportion of oxygen than fibrine, 

 and has sulphur for a constituent part, which, however, cannot be 

 detected while the albumen is entire, any more than the iron while 



* Phil. Tram. 1818. p. 187. f Medical Literature, p. 545. 



J Phil. Trans. 1819. p. 2 4 !iq. 



