478 Edwin G. Kirk. 
Yards. Half a minute after the instantaneous death of the mother, 
by cerebral concussion, the uterus was cut out, and immediately 
opened. The embryos were removed, and their greatest length 
in the natural attitude along a straight line (Minot’s System. 
Vide Minot, ’03, p. 356) determined by calipers, and recorded in 
centimeters. The stomach was then rapidly removed, the subdi- 
phragmatic oesophagus and also a small bit of the duodenum 
having been left attached in the earlier ones for orientation. The 
stomach was then slit open along either anterior or posterior 
side, and filled with fixing fluid. Stomachs from embryos of over 
6 cm. length are distended with a clear, glairy, mucoid fluid, 
often of a greenish tinge. This must first be allowed to escape, as 
otherwise fixation is unsatisfactory. After being filled with fixing 
fluid, the stomach is immersed in it and placed in the dark. After 
a little practice the whole operation need take no longer than 
half a minute. This fixation immediately after death is of great 
importance in obtaining accurate pictures of intracellular condi- 
tions, especially of the zymogenic, mucus and parietal cell gran- 
ules. In dealing with embryos of over 12 cm. some of the stomachs 
were treated as described above, others were subdivided, great 
care being taken to preserve the identity and orientation of the 
pieces. The series included embryos of 2 to 29 em. length at inter- 
vals of 4 cm. Generally, several stomachs of each stage were 
used; some for sagittal sections, thro’ the whole length where 
practicable, some for cross sections. In all cases the sections were 
cut serially, and this is very necessary, as will be seen later, for 
the correct interpretation of certain appearances. 
I tried many methods of fixation, but finally settled down to the 
use of Bensley’s fluid as giving the best general results.'. Modified 
1 This consists of equal parts of 3 per cent aqueous K2Cr207 and sat. HgC12 in 
100 per cent alcohol, mixed just before using. The cloudy precipitate is to be dis- 
regarded. The material is fixed in the dark from 30 minutes to 2 hours, according 
to thickness. It is then transferred to50 per cent alcohol, in which, with frequent 
changes, it remains several days; then to 70, 80 and 95 per cent a day or two, with 
several changes in each; finally to 100 per cent and then bergamot, bergamot and 
paraffine, and finally paraffine. At no time until after impregnation with paraffine 
should the material be subjected to the action of water. Otherwise, as Bensley 
pointed out (1903-4) the zymogen granules and mucigen are preserved poorly or 
not at all. 
