250 ANNUAL EEPORTS OF DEPAETMENT OF AGEICULTUEE. 



of the animals to the gas for 25 minutes and no bad effects from the 

 treatment were noted. 



The sulphur dioxid gas treatment was also tested on chronic cases 

 of horse mange, but without success. The experiments indicate that 

 the gas at the concentration used does not destroy all mites or eggs 

 present. 



Further tests of sulphur dioxid gas were made to determine its 

 effect on cattle lice. The results show that 20 minutes' exposure to 

 the gas destroys all lice, but does not destroy the eggs, and that louse 

 eggs will hatch after 30 minutes' exposure to the gas. 



Experiments were made to ascertain a satisfactory treatment for 

 grub-in-the-head of sheep, a cause of considerable loss, especially to 

 buck herds. Many of the grubs, especially in the early stages of de- 

 velopment, apparently can be destroyed by the application of equal 

 parts of chloretone (trichlorbutyl alcohol) and ether, or liquid petro- 

 latum and chloroform applied as a spray with an ordinary atomizer. 

 Further work is necessary to ascertain whether the treatment is prac- 

 ticable and effective. 



TESTS OF ANTHELMINTICS. 



Further studies have been made on the use of carbon tetrachlorid 

 as an anthelmintic. This drug, first proposed as a remedy for hook- 

 worm infestations by this laboratory in 1921, has now been exten- 

 sively used throughout the world for the treatment of human beings 

 infested with hookworms, over 60,000 cases having been treated in 

 Fiji alone, and numerous other cases in the United States, Mexico, 

 Jamaica, Dutch Guiana, Brazil, the Philippines, Borneo, Ceylon, 

 Samoa, China, Japan, Australia, India, England, and elsewhere. In 

 the spring of 1923 it was admitted to the list of new and nonofficial 

 remedies and is now under consideration for admission to the United 

 States Pharmacopoeia. Clinical experience and animal experiments 

 have borne out the experimental evidence obtained in this laboratory 

 to the effect that this drug is distinctly more effective in removing 

 hookworms than are chenopodium, thymol, betanaphthol, or any 

 other drugs used to remove hookworms. It is also cheaper than any 

 of these drugs. In the great majority of cases it causes but mild and 

 transient symptoms of discomfort, and patients who have taken this 

 drug and any other hookworm remedy regularly express a prefer- 

 ence for carbon tetrachlorid. As a rule, patients can do the usual 

 day's work on the day of treatment, whereas with other drugs pa- 

 tients usually lose a day or several days from work, a matter of great 

 importance in mass treatments and in the hospitalization item for 

 civilians or armed forces. 



Clinical experience, however, shows that there are certain persons 

 and animals susceptible to bad effects from the drug, and studies 

 have been carried out with a view to finding some way to make this 

 drug safe for these exceptional cases. Investigators at Johns Hop- 

 kins University having shown that Epsom salt administered at the 

 same time as other drugs prevents to a large extent, or even entirely, 

 the absorption of the other drugs, experiments to test the effects of 

 the administration of Epsom salt with carbon tetrachlorid to dogs 

 were undertaken in the Zoological Division. The experiments with 

 huge doses of carbon tetrachlorid (up to 20 cubic centimeters per 



