108 THE BLOOD. 



certain proportion passes through without parting with its 

 oxygen, a fact which has also been demonstrated by analysis, 

 and consequently retains its red color. The explanation in 

 cases of syncope is probably the same ; though this is merely 

 a supposition. Even during secretion, a certain quantity of 

 carbonic acid is formed in the gland, which, according to 

 Bernard, is carried off in solution in the secreted fluid. 1 



It may be stated in general terms that the color of the 

 blood in the arteries is bright red ; and in the ordinary veins, 

 like the cutaneous or muscular, it is dark blue, almost black. 

 It is red in the veins coming from glands during secretion, and 

 dark during the intervals of secretion. 



Anatomical Elements of the Blood. 



In 1661, the celebrated anatomist, Malpighi, in examining 

 the blood of the hedgehog with the feeble and imperfect 

 lenses at his command, discovered little floating particles 

 which he mistook for granules of fat, but which were the 

 blood-corpuscles. He did not extend his observations in 

 this direction; but a few years later (1673), Leeuwen- 

 hoek, by the aid of simple lenses of his own construction, 

 varying in magnifying power from 40 to 160 diameters, first 

 saw the corpuscles of human blood, which he minutely 

 described in a paper published in the Philosophical Trans- 

 actions, in 1674. To him is generally ascribed the honor of 

 the discovery of the blood-corpuscles. About a century later, 

 William Hewson 3 described another kind of corpuscles in 

 the blood, which are much less abundant than the red, and 

 whicli are now known under the name of white globules, or 

 as they have lately been called by Kobin, leucocytes. 



Without following the progress of microscopic investiga- 



1 BERNARD, op. cit., tome i., p. 346. 



3 The Works of William Hewson, F. R. S., Sydenliam Society edition, London, 

 1846. 



