W. Nicoll 
177 
but not for three. The eggs in the control untreated sample lived for 
at least a fortnight. 
With the same sample of faeces a series of experiments was made 
with some highly hygroscopic salts such as potassium acetate, calcium 
chloride and silver nitrate, the object being to ascertain if the absorption 
of such highly soluble salts would prevent the development of the eggs. 
Calcium chloride and silver nitrate effectually did so when used in the 
proportion of 1 to 5, but potassium acetate which is an equally soluble 
salt failed to kill the eggs in 24 hours even when used in the proportion 
of 1 to 2. With this strength, however, the eggs did not survive for 
two days. From this it may be suspected that the greater effect of 
calcium chloride and silver nitrate was largely a poisonous one. 
These three salts, it must be remarked, were used merely to test 
the effect of such salts and not with any view to their practical or general 
employment. It is obvious that they are quite unsuitable on a practical 
scale. 
III. In this series of experiments weighed quantities of salt and 
faeces were used as before but the salt, instead of merely being sprinkled 
on the surface, was thoroughly mixed up with the faeces. Quantities 
of salt varying from 0-3 to 1-5 times the weight of the faeces were 
used. At intervals of 24 hours small portions of these mixtures were 
removed, thoroughly washed in water to free them fropi salt, and the 
residue plated. A control sample of faeces was also treated in the" 
same way. 
At the end of 24 hours examination of the faeces showed that most 
of the eggs in the control sample were alive and rapidly developing, 
while those in the other samples appeared to be all dead. Plate cultures 
from the control gave numerous active larvae while in the case 
of the others the results were negative, although the cultures were 
incubated for a week. At the end- of another 24 hours cultures were 
again made. The results were the same as before with the important 
exception that the cultures from No. 1 (that with the least salt) pro¬ 
duced a single vigorous larva which developed normally and eventually 
became ensheathed. At three further intervals of 24 hours cultures 
were again made, but except in the case of the control sample, no 
larvae were produced. The control sample remained productive for a 
considerable time afterwards. 
The conclusions to be drawn from this series are that when faecal 
material is thoroughly mixed with half its weight of salt development 
