WATER AND SOLID CONSTITUENTS OF BLOOD AND SERUM. 29 



prove that the office of the blood-corpuscles is not solely the introduction of oxygen, 

 and the carrying out of carbonic acid. The following facts will show that the 

 liquor sanguinis is also active in the performance of these important offices. 



In the capillaries and bloodvessels, the colored corpuscles rush along in the 

 centre of the streams, whilst pure liquor sanguinis alone is in contact with the 

 walls of the vessels. In the capillaries of the lungs, the oxygen, from this arrange- 

 ment, must necessarily be absorbed first by the liquor sanguinis. Again, in no case 

 do we find the organic cells, the active agents in all secretion and excretion, in 

 immediate contact with the blood-corpuscles. They are separated from them by 

 the coats of the capillaries, and a structureless basement membrane. The same is 

 true of the anatomical elements of the muscular tissue. From whence do they 

 derive oxygen, a continuous supply of which is absolutely necessary for the life 

 and activity of every living molecule of organized beings? The same argument 

 will also prove that the blood-corpuscles are not the sole agents in the conveyance 

 of carbonic acid gas out of the organs and tissues. 



These conclusions can be sustained by numerous examples. 



Do we find blood-corpuscles in plants? Do we find blood-corpuscles in the lowest 

 orders of invertebrate animals? These bodies absorb oxygen, and give out carbonic 

 acid gas, notwithstanding the absence of blood-corpuscles. Spallanzani 1 has long 

 since demonstrated that all organized bodies, whether living or dead, possess the 

 property of absorbing oxygen and giving out carbonic acid gas. 



We do not for one moment deny that one important office of the blood-corpuscles 

 is the absorption of gases, for it has been often demonstrated that blood containing 

 its corpuscles possesses far greater powers of absorbing oxygen, nitrogen, and car- 

 bonic acid than pure serum. We wish to show that this is not the sole office of 

 the blood-corpuscle, because it is performed by the liquor sanguinis, and all organic 

 matters, whether living or dead; and respiration is carried on in plants and the 

 lowest animals, which are without blood-corpuscles; and an increase in the number 

 of blood-corpuscles is not necessarily followed by an increase in the temperature. 



What, then, are the principal offices of the blood-corpuscles, and what does an 

 increase in their numbers denote? 



These questions can only be answered by a consideration of their constitution, 

 and their relations with the liquor sanguinis by which they are surrounded. 



Each corpuscle is a cell, resembling, in its nutrition, growth, and general struc- 

 ture, the active agents in the formation, elaboration, and separation of all secretions 

 and excretions. Their cell walls possess the property of separating from the sur- 

 rounding medium certain peculiar organic and mineral compounds. If a blood- 

 corpuscle be placed in water, it swells up, and finally bursts. If it is placed in a 

 solution denser than its internal contents, they pass out more rapidly than the 

 exterior solution passes in, and the cell wall shrivels up. The same physical laws 

 of endosmose are at work in the animal economy. A mutual action and reaction 

 is incessantly carried on between the interior contents of the blood-corpuscles and 

 the exterior liquor sanguinis. Whenever water, or liquids of low specific gravity, 



1 Memoirs on Respiration, by Lazarus Spallanzani. Edited by John Lenebier. London, 1805. 



