lO 
SHEEP SCAB. 
*Crude Aniline — Dissolved in water in the proportion of one 
to 800 by weight. 
* Phenyl Hydrazine — Dissolved in water in the proportion of 
one to 500 by weight. 
MANNER OF APPLYING THE DIPS. 
Unless otherwise stated in the notes upon the different dips, 
it will be understood that all were used at about 95 degrees 
temperature, and that the time of dipping was two minutes. 
In the laboratory experiments the mites were in each case pro- 
cured on the day of the experiment by pulling wool from live 
scab. The mites were treated by dipping the wool that they were 
on into the various substances used, and, after two minutes, re- 
moving the wool and hanging it on pins to dry. This was thought 
to come as near the natural conditions as it was possible in the 
laboratory. 
In most cases the dipping was done between five and six in 
the afternoon, and the first examination made between nine and 
ten the next morning. Examinations were made under a dissect- 
ing microscope, and all mites that could not be induced to move 
were accounted dead. When possible, a second or even a third 
examination was made, but the pressure of other work often made 
this impossible. 
It must not be concluded that all dead mites found after 
treatment are necessarily dead because of the treatment, as an 
examination of the check lots will show that when removed 
from the sheep and kept in a warm atmosphere the mites died 
rapidly after the first few hours when untreated. 
LABORATORY EXPERIMENTS. 
The final test of any dip must be upon sheep infested with 
scab. Laboratory tests are of much value to the experimenter 
in that they can be conducted in larger number under conditions 
that can be more completely controlled, and they give informa- 
tion that greatly aids in the selection of dips of promise and in 
the rejection of those that seem worthless. xVs very little ex- 
perimental wmrk has been done with sheep dips as yet in this 
country, and, as it is probable that the subject is to attract con- 
♦Suggested and prepared by Dr. W^ P. Headden. 
