180 
Development of Hook-worms 
attention was paid to the length of time (in days) required by the larvae 
to hatch out in each case. The results are given in the subjoined 
table. (The figures in brackets indicate the number of days required 
for the eggs to hatch); 
May 11 
12 
13 
14 
15 
16 
17 
18 
19 
20 
21 
r 
+ (4) 
+ (3) 
- 
- 
- 
- 
- 
- 
- 
- 
2. 
+ (4) 
+ (3) 
- 
- 
- 
- 
- 
- 
- 
- 
3. 
+ (2) 
+ (3) 
- 
- 
- 
- 
- 
- 
- 
- 
4. 
+ (2) 
+ (1) 
+ 
(2) 
(3) 
+ 
(3) 
+ 
(5) 
- 
- 
- 
- 
5. 
+ (2) 
+ (1) 
+ 
(2) 
-1- 
(1) 
+ 
(1) 
+ 
(2) 
+ (2) 
+ (1) 
+ (3) 
+ (3) 
From this experiment it is obvious that 8 % of salt is not sufficient 
to kill all the eggs within 48 hours, but it is efficient within three days. 
It is not, however, any more efficient than 4 %. With 2 % of salt 
a period of at least six days was required to kill all the eggs or prevent 
them developing. The control specimen showed that the eggs used in 
the experiment were capable of developing into active larvae for at 
least ten days. 
With regard to the time of hatching it is evident that in Nos. 1 and 
2 the average time was about three and a half days, whereas in the 
control the time was under two days. There can be little doubt from 
this that the admixture of salt caused a very marked retardation in 
the development of the hook-worm eggs. 
VI. This series was arranged to contrast the effect of sprinkling 
as opposed to mixing the salt with the faeces. The results, however^ 
are not satisfactory, apparently because the faeces were not suitable. 
The faeces were very moist and contained a moderate number of 
Ankylostoma eggs together with numerous eggs of Trichmris trichiura. 
The quantities of faeces and salt used were as follows: 
Weight of 
faeces 
Weight of 
sSt 
Percentage 
it salt 
1. 
1-5 g. 
0-23 g. 
15% 
Salt sprinkled on 
2. 
20 
016 
8% 
3. 
1-3 
— 
0 
Control 
4. 
2-26 
018 
8% 
Salt thoroughly mixed 
5. 
1-6 
0-24 
15% 
» ft 
The results of these experiments were: 
July 18 
19 
20 
21 
22 23 24 
1. 
+ (3) 
+ (3) 
- 
- - 
2. 
+ (3) 
+ (3) 
- 
- - 
3. 
+ (3) 
+ (3) 
+ (3) 
+ (3) 
4. 
+ (3) 
+ (4) 
- 
- - 
6. 
+ (3) 
- 
- 
- - 
23 
24 
