40 MEDICAL ENTOMOLOGY 



purposes, or as flowers of sulphur, to be mixed with tobacco 

 dust, as above, or in the form of an ointment, against scab and 

 mange mites on domesticated animals, or for human scabies 

 (itch). An effective sulphur ointment is prepared as follows: 



Sulphur, i oz., carbonate of potash y oz. and lard 4 oz. 



Examine some flowers of sulphur and a sulphur cone. 



1. Formaldehyde is a splendid disinfectant and a good stomach 

 poison for flies, but is useless as a spray against insects. As a 

 fly poison formaldehyde purchased in about 38% to 40% solu- 

 tion must be diluted with water to about 2% or even less, that 

 is, one part to twenty or thirty parts of water. This must be 

 made accessible to the flies in shallow vessels. 



Examine some formaldehyde. 



m. Oil of Citronella is a good repellent against mosquitoes, 

 black gnats, etc. It should be applied full strength to the hands 

 and face. 



Examine a sample of oil of Citronella. 



m. Larkspur (Delphinium staphisagria) is useful in the de- 

 struction of both the human head louse and the crab louse. It 

 is ordinarily used in the form of tincture or ointment (Unguen- 

 tum Staphisagria) 10%. 



Examine a sample of tincture of larkspur. 



EXERCISE 23a 



THE AMCEB.S: 

 PHYLUM PROTOZOA, CLASS RHIZOPODA (SARCODINA), ORDER 



AMCEB^A 



A. In prepared specimens on slide of Entamoeba histolytica, 

 the amoeba of Oriental dysentery, note the following: (The 

 student is cautioned against confusing these with leucocytes 

 and foreign matter.) 



