1887] Microscopy. 681 
contain a small nucleus, a clump of yellow pigment, or a bod 
closely resembling a small red blood-corpuscle. To control this 
experiment we may make use of another one,—that is, we may 
cover a fresh drop of blood with a cover-slip and seal it from 
the air Thus the blood coagulates slowly, and we may study 
directly the changes the forms undergo during coagulation. 
The granules of the “ eosinophilous cells” may be seen to become 
larger, less distinct, and disappear. The “eosinophilous cell” has 
eveloped into the “‘amcebocyte.” The “hzmatoblasts’” assume 
the forms mentioned above, the nucleus and cell as a whole be- 
come round, and at length send out pseudopodia in every di- 
rection, so that it is impossible to distinguish them from “ amce- 
bocytes.” The “amcebocytes,” in their turn, at first stretch out 
their pseudopodia in a lively manner, then gradually attach 
themselves to the cover-slip, where they spread themselves over 
a large surface, and resemble the “endotheloid cells” with their 
broad borders of hyaline substance and the granulated proto- 
plasma about the nucleus. If we now bring together the facts 
we have observed,—1, in instantly fixed blood; 2, in blood fixed 
after intervals; 3, in fresh blood,—we find that the: first three 
kinds of white blood-corpuscles may at length become “ endo- 
theloid cells,” 
velopment of the red blood-corpuscles. In the course of his 
vations of a series of frogs he noticed that the “ ammenzel- 
"The edges of the cover-slip must be thoro hly free from moisture, a bit of 
‘ a wax dropped upon Eri Sorat: and the wax then diwi along the edges of 
ver-slip with a heated iro wire. 
X» 
ALTIN 
