on the Blood and Animal Tissues. 1 35 



markable and sudden alteration in the appearance of the par- 

 ticles than water does. With a rapidity, which in spite of 

 every precaution, the eye almost invariably in vain attempts 

 to follow, they change their flattened for a globular form, which 

 from the brightness and distinctness of the images which they 

 reflect as convex lenses, must be nearly perfect. 



Contrary to Sir Everard Home's remark, that the particles 

 in their perfect and entire state are not disposed to arrantre- 

 ment, it is in this state only that vve have found them run into 

 combinations, which they assume with considerable regularity. 

 In order to observe this tendency of th.e particles, ^a small 

 quantity of blood should be placed betweim two slips of glass. 

 In this way the attraction exerted by one of the pieces of glass, 

 counteracts that of the other, and the mutual action of the 

 particles on each other is not interfered with, as is necessarily 

 the case when only one slip is employed. 



When the blood of man, or of any other animal having cir- 

 cular particles, is examined in this manner, considerable agi- 

 tation is at first seen to take place amongst the particles; but 

 as this subsides they apply themselves to each other by their 

 broad surfaces, and form piles or roideatix which are some- 

 times of considerable length. These roideaiix often again com- 

 buie amongst themselves, the end of one being attached to the 

 side of anotiier, producing at times very curious ramifications. 



When blood containing elliptical particles is examined in 

 the same manner, it exhibits a not less remarkable but very 

 different mode of arrangement. Though they are applied to 

 each other by some part of their broad sides, they are not so 

 completely matched one to another, as is the case with circular 

 particles; and instead of placing themselves at right angles to 

 the glass, with their edges presented to its surlkce, they are 

 generally seen nearly parallel to it, one particle partially over- 

 laying another, and their long diameters being nearly in the 

 same line. The lines thus formed are subjected to a kind of 

 secondary combination, in which several assume to themselves 

 a common centre, wlience they diverge in radii. It is by no 

 means rare to see several of these foci in the field of the mi- 

 croscope at one time. The particles at these points appear 

 crowded, confused, and misshapen. This tendency to arrange- 

 ment IS perliaps not to be wholly attribtited to the ordinary 

 attraction existing between the particles oif matter, but is pro- 

 bably to a greater or less degree dependent on life; since we 

 have not only observed that the aggregating energy is of dif- 

 ferent force in the blood of dilFerent indiiiduals, but that in 

 the blood of the same individual it becociies more feeble the 

 Ioiig<r It has i)ecri removed from the body. At the same time, 



we 



