1917] Bishopp and Wood—Experiments with Sodium Fluoride 189 
about one ounce being used to each animal, and in others it was 
applied as a dip, the sodium fluoride being dissolved in water at 
the rate of one ounce to the gallon. In all of these tests the de- 
struction was complete and the lesions promptly healed. 
Experiments conducted thus far with sodium fluoride clearly 
show its efficacy in the case of Mallophaga on domestic animals. 
Owing to the comparatively high price of the substance (about 
50 cents per pound) it is inadvisable to recommend its use in the 
form of a dip for large animals as other equally effective dips which 
are much cheaper may be used. The tests indicate, however, that 
the substance may be very useful for the winter treatment of 
animals, especially in the northern states where dipping during 
the cold weather is impractical. Attention also should be called 
to the fact that infestations are normally heaviest during the 
winter and spring months, just at a time when the practice of dip- 
ping might be dangerous. The application of sodium fluoride 
with a dust gun is not laborious, and since it appears that only 
about one ounce of material per animal is necessary the treatment 
would not be expensive. Our preliminary tests also indicate that 
if all animals in a herd are treated at one time in this way, one 
application will be sufficient. Although we have found that lice 
may live from 7 to 15 days when removed from the host it appears 
that under usual circumstances sodium fluoride is retained in the 
hair for sufficient length of time to destroy any lice which may 
happen to return to the host. 
While there appears to be some possibilities in the use of sodium 
fluoride against sucking lice the experiments thus far conducted 
indicate that it can not be relied upon for use against any of the 
members of this order. 
