112 Transactions of the JEtoyal Microscopical Society. 
glass slide and covered with the plate of thin glass, a number of 
blood-corpuscles are observed to change in various manners, and in 
a slighter or greater degree, their original form. In some instances 
the convex peripheral portion of the corpuscle appears to shrink in 
thickness at one point, while the rest of it swells and gains in 
diameter, so that the whole body assumes a wedge-like form (Fig. 
60, a and /). In other instances the blood-corpuscle assumes the 
form of a shallow basin, an appearance which is very probably 
caused by a contraction of the convex border of only one surface, 
by which process the concavity on this surface increases in depth, 
while the other surface is rendered convex instead of concave. If 
the contraction continues, the corpuscle assumes the form of a deep 
cup. Whether during this process the central portion increases in 
thickness, while the convex periphery is rendered thinner by the 
contraction, is difficult to determine ; but that the contraction takes 
place only on one surface of the convex margin is obvious ; for if 
it occurred throughout the whole margin, the corpuscle would not 
become cup-shaped, but would preserve its original form of a disk, 
though its central portion might gain in thickness, while the con- 
cavities of its surfaces would decrease in depth or entirely disappear. 
Sometimes the convexity of these cup-shaped forms terminates in a 
conical protuberance, as seen in Fig. 60, e. There is another very 
singular form observed, difficult to describe, but resembling in some 
respects the wedge-like form, with the exception that -the narrow 
portion of the wedge, instead of being straight, assumes here 
the form of a Y, showing that the body must be three-sided 
(Fig. 60, g). _ 
Intermediate forms, similar to those above described, are ob- 
served (Fig. 60, h, c, and d ) ; but it will be noticed that in all these 
instances it is only a portion of the protoplasm of the blood-cor- 
puscle which is contracting, while the rest is expanding in com- 
pensation of the contraction. There are, however, other changes 
occurring in the form of the corpuscles, owing to a contraction of 
the protoplasm throughout the whole body, and accompanied by a 
considerable diminution in size. As the result of such a contrac- 
tion, we may regard those familiar forms of blood-corpuscles, 
generally compared to a mulberry or a thorn-apple. These, when 
occurring on the blood-corpuscles of fresh blood, and without the 
action of a reagent, have generally been attributed to the evapora- 
tion of the liquor sanguinis. With the increase of the density of 
this liquid, namely, an exosmotic current from the blood-corpuscles 
is supposed to be induced, causing shrivelling of the corpuscles. If 
this view were correct, those corpuscles nearest to the edge of the 
drop of blood should first undergo the changes in question. But 
this is not the case ; on the contrary, single mulberry or thorn- 
apple shaped blood-corpuscles are observed among the mass of 
