The Structure of Colored Blood- Corpuscles. 287 



whose edges are hollow, and either empty, or filled with a 

 subtile fluid." 1 He detailed the following experiments: — 

 "Take a drop of the blood of an animal that has large parti- 

 cles, as a frog, a fish, or what is still better, of a toad; put 

 this blood on a thin piece of glass, as used in the former ex- 

 periment, and add to it some water, first one drop, then a 

 second, and a third, and so on, gradually increasing the 

 quantity ; and in proportion as water is added, the figure of 

 the particle will be changed from a flat to a spherical shape, 

 * * * * * jj- w ju ro ][ fl own t] ie jrlass stao-e smouthlv, 

 without those phases which it had when turning over when 

 it was flat ; and, as it now rolls in its spherical shape, the 

 solid middle particle can be distinctly seen to fall from side 

 to side in the hollow vesicle, like a pea in a bladder." He 

 added : "From the greater thickness of the vesicles in the 

 human subject, and from their being less transparent when 

 made spherical by the addition of water, and likewise from 

 their being so much smaller than those of fish or frogs, it is 

 more difficult to get a sight of the middle particles rolling 

 from side to side in the vesicle which has become round ; but 

 with a strong light (these experiments were all made with 

 daylight, in clear weather), and a deep magnifier, I have 

 distinctly seen it in the human subject, as well as in the frog, 

 toad, or skate." Another experiment he describes thus : " If 

 a saturated solution of any of the common neutral salts be 

 mixed with fresh blood, and the globules (as they have been 

 called, but which for the future I shall call flat vesicles) be 

 then examined in a microscope, the salt will then be found to 

 have contracted or shriveled the vesicles, so that they appear 

 quite solid, the vesicular substance being closely applied 

 all around the central piece." Furthermore, " the fixed 

 vegetable alkali, and the volatile alkali, were tried in a 



(1) "On the Figure aud Composition of the Bed Particles of the blood, commonly calied 

 the Red Globules." Philosophical Transactions vol. 63, 1 art II. p. 310 et seq. (Read June 

 17th and 2ith, 1773.) "A Description of the Red Particles of the Blood in the human subject 

 and in other animals, being the remaining Part of the Observations and Experiments of the 

 late Wm. Hewson." By Magnus Falconer, London, 1777, p. 221 et teq. 



