CHAPTER V. 



CONTAINING AN ACCOUNT OF THE MANNER IN WHICH THE RED 

 PARTICLES OF THE BLOOD ARE FORMED, DEDUCED FROM THE 

 EXPERIMENTS AND OBSERVATIONS RELATED IN THE PRECEDING 

 CHAPTERS. 



SECT. 78. IT hath been shown, in a paper delivered by the 

 late Mr. Hewson, 1 and read June 17th and 24th, 1773, entitled, 

 " An account of the Figure and Composition of the Red Par- 

 ticles of the Blood, commonly called the Red Globules," that 

 these red particles are not globules, as was generally believed, 

 but that each particle is a compound body consisting of two 

 parts, viz. an external portion, which, from its resemblance to 

 a small bladder, is called a vesicle ; and an internal, contained 

 in the centre of this vesicle, which is called the central par- 

 ticle (cxxxiv); and that these particles while circulating in 

 the blood-vessels in their natural state, are not spheres, but 

 round and flat, resembling a piece of money (cxxxv). 



SECT. 79. This fact has been proved by experiments ; first, 

 if the red particles of the blood be diluted with fresh serum, 

 and examined with a microscope, their flat figure may be im- 

 mediately discerned, and the shape of the particles remains 

 unaltered; but if a small quantity of water be mixed with 

 these particles, they are immediately transformed from a plane 

 to a sphere, the vesicle will gradually dissolve (cxxxvi), and 

 dissolving becomes transparent, at which time the central par- 

 ticle may be seen rolling from side to side like a pea in a 

 bladder ; the vesicle at length bursts, and the central particle 

 will be entirely disengaged from it ; but if a drop or two of a 



. ' Vide Chapter I. 



(cxxxiv.) See Notes en and cxxxvii. 

 (cxxxv.) See Note xcv, pp. 215-16. 

 (cxxxvi.) See Note xciv, p. 215. 



