February, '17] LAMSON: MERCURIAL OINTMENT FOR HEN LICE 73 



time. The more dilute mercurial preparations lost their effectiveness 

 as the amount of mercury was diminished. 



After this one hundred and four chickens were treated in the 

 laboratory where they could be under close observation. Here tests 

 were made with these preparations, particularly the mercurial oint- 

 ments of various strength. The ointment was applied to different 

 parts of the body such as on the head, under the wings and under the 

 anus. The application of the mercurial ointment diluted to the 

 strength of one part to two parts of vaseline was most effective for 

 the largest number of birds when applied under the anus or vent. 

 This was probably due to the fact that the two species of body lice 

 that were more numerous upon birds studied laid their eggs in this 

 region. The application was nearly as effective when placed under 

 the wings and least effective when placed only on the back of the 

 head and neck though for the hens affected with the head and body 

 lice it would give the best results to apply to this region as well as 

 under the anus. 



The method of application was to take an amount about the size 

 of a pea and rub it into the base of the feathers. This adheres to the 

 finer portion of the hen's covering and remains there for a long time. 

 A hen thus treated was kept in a glass case for a time under observa- 

 tion; many dead lice were found on the floor of the case while but 

 three live lice were seen to leave her. 



Some little confusion occurs in the use of the term mercurial 

 ointment and blue ointment. Mercurial ointment contains 50 per 

 cent of metallic mercury with 50 per cent petrolatum (vaseline). 



Blue ointment is a mixture consisting of 67 per cent mercurial 

 ointment and 33 per cent vaseline, and, therefore, contains about 33 

 per cent of mercury. 



Mercurial ointment costs $1.75 per pound while blue ointment 

 costs $1.50 per pound. It is, therefore, cheaper to buy the mercurial 

 ointment and dilute it with vaseline, using one part of the former to 

 two of the latter. To mix this it is best to place the ingredients on 

 . a pane of glass and work them together with a case knife, being sure 

 that the mixing is thoroughly done. Place in a receptacle and label. 

 An ounce of this ointment is sufficient to treat from sixty to seventy 

 hens while the application can be made almost as fast as the hens can be 

 caught. In that much time is likely to be spent in catching the fowl, 

 it is best to do this work after the birds have gone to roost. The cost 

 involved to buy and apply this ointment is less than one-half cent for 

 each hen. To be sure this should not be used for the setting hens on 

 account of the effect it might have upon the respiration of the chick 

 embryo, but if applied one or two months before, the hens will not be 



