c d e f cf

Fig. 12. Diagrammatic Bepresentation of the Manner in which a Leucocyte
Traverses the Wall of a Capillary Blood- Vessel. (After Craig), a, Leucocyte
before penetrating; 6, leucocyte sending off process and granules beginning to
withdraw to farther end of cell; c, leucocyte partly through wall, granules at
upper end of cell; d, granules passing through the wall; e, granules arranged
in the portion of the leucocyte farthest from vessel; /, leucocyte, after pene-
tration, resuming its original condition; g, leucocyte swept from wall, showing
retention of the clear penetrating proce.ss.
80



262. Note the elasticity of the red corpuscles, observing the way
in which they bend and later regain their normal form.
263. Study of inflammatory conditions. Remove the cover-
glass and absorib the fluid on the weib ; touch the middle of the web
with the tip of a glass rod that has been dipped in creosote (or a
2% solution of croton oil in olive oil) leaving a minute drop on the
web. Put on a cover-glass as before and examine with the micro-
scope. If not successful with the web, try the tongue or mesentery.
264. Note the dilation of the arteries, the more distinct
appearance of the capillaries, and the enlargement of the veins,
accompanied by a quickening of the current.
265. Note a little later, the slowing of the current, the vessels
remaining dilated.
266. Note that the leucocytes increase in number in the per-
ipheral zone of both arteries and veins ; in the latter the leucocytes
begin to cling to the sides, temporarily at first and then permanently.
