W. Nicoll 
185 
in a similar manner with the exception that it was first sprayed with 
water for five minutes and the process repeated every 24 hours, the 
surplus water being drained off. Two control samples were kept 
covered. 
The first and second portions yielded larvae for two days but none 
thereafter. The controls produced larvae for over a week when the 
experiment was discontinued. 
This appears to show that in the natural course of events when the 
faecal material'is freely exposed in the absence of moisture the hook¬ 
worm eggs may die off within three days and that the moistening of 
the material every 24 hours does not prolong the life of the eggs. 
XIII. The next series was intended to test the effect of direct 
sunlight. The. faeces were exposed under various conditions to the 
direct rays of the sun, and for the purpose of comparison other portions 
of faeces were exposed under similar conditions in the shade, out of 
doors and in the laboratory. The material used was solid and fairly 
dry. 
The various portions were placed as follows: 
1. On paper ] Exposed to 
2. In covered Petri dishes direct sun- 
3. - In open Petri dishes surrounded with w'ater [ light in the 
4. In covered Petri dishes surrounded with water/ open air. 
5. In open Petri dishes 
6. In covered Petri dishes 
7. In open Petri dishes surrounded with water 
8. In open Petri dishes 
9. In covered Petri dishes 
10. In open Petri dishes surrounded with water 
The experiment was started at 4 p'.m. when the shade temperature 
was 95° F., but during the course of the experiment it fell to 90-5° F. 
Earlier in the day the temperature had reached a maximum of 104-2°. 
The wet bulb temperature rose during the experiment from 78-6° to 
80-6° F. The solar radiation registered 154-5° F. at 3 p.m. During 
the whole course of the experiment the sun continued to shine 
brightly. 
Cultures were made from Nos. 5-7 at 5 p.m. and again at 
6 p.m. 
I Outside in the 
j shade. 
} In room in the 
shade. 
