830 
Races of Entamoeba histolytica 
after fixation were made within five minutes of the apphcation of the 
fixative, but in some cases they were repeated at intervals up to one and 
a half hours later. When this was done we found the prolonged action of 
the fixative produced no subsequent change in size. The measurements 
in every case were made by one of us and checked by the other before 
being recorded. The cysts were from an infection in which they were of 
large size, and thus convenient for measuring. 
Table III. 
Dimensions of cyst in microns 
Cyst No. 
Before fixation 
After fixation 
Effect of fixation on size of cyst 
1 
13-5 xl5 
13-5 xl5 
None 
2 
1.3-5 X 12-75 
12-75x13-5 
None (sKgbt change of shape) 
3 
14-25 X 14-25 
14-25 X 14-25 
None 
4 
13-5 xl3-5 
13-5 X13-5 
None 
5 
13-5 xl5 
13-5 xl5 
None 
6 
14-25 X 13-5 
14-25 X 13-5 
None 
7 
12-75 X 12 
12-75x12 
None 
8 
15 X 14-25 
15 X 14-25 
None (slightly distorted) 
9 
15-75 X 14-25 
15 X 15 
None (slight change of shape) 
10 
14-25 X 13-5 
14-25 X 13-5 
None 
11 
15 X 14-25 
15 X 14-25 
None (slightly blistered) 
12 
13-5 xl3-5 
13-5 xl3-5 
None (slightly blistered) 
13 
14-25 X 12-75 
15 xl2 
None (change of shape) 
14 
16 X 14-5 
16 X 14-5 
None. 
From these experiments we conclude that living cysts, when fixed 
with the solution which we have used, undergo no change in size what¬ 
ever as the result of fixation. 
The efiiects of staining, dehydration, clearing, and mounting in balsam 
were studied under the microscope in the same way as the effects of 
fixation: that is to say, the fixative was removed with the pipette, and 
other reagents substituted successively as required. We give below the 
results of three such experiments in detail. 
Expt. 1. (Cyst No. 4 of Table III). 
Medium in which cyst was examined 
Gelatine jelly (living cyst) ... 
Fixative (after 5 mins.) 
Fixative (after 30 mins.) 
70 % alcohol. 
Paracarmine (20 mins.) 
Absolute alcohol 
Xylol. 
Balsam (immediately) 
Balsam (after 1| hrs.) 
Dimensions 
13-5/x X 13-5/.t 
13-5q X 13-5|a 
13-5/x X 13-5;a 
13'5p, X 13'5p. 
13-5u X 13-5/i 
12-75/x X 12-75^ 
12q. X 12p, 
12/i X 12 ^ 
