THE COMMON SHEEP-SCAB. 71 



tection. Separating with the hand the wool of infested ani- 

 mals, the presence of mites w^ill become evident if we find 

 round spots upon the skin, which appear whitish where the 

 epidermis is a little elevated, and where the lymph forms 

 yellowish thin deposits that are easily lifted with the loos- 

 ened w^ool. In some cases the animals show pain if scratched, 

 instead of pleasure. The skin of infected animals, if butch- 

 ered, show upon their under side red points. The disease 

 always starts from small spots, and spreads but very grad- 

 ually. If neglected, the scabs become thick and of a brown 

 color, as if soaked with oil; eventually the skin, entirely de- 

 nuded of wool, becomes wrinkled, and between the wrinkles 

 cracks appear. If the further increase of the scab-mites is 

 not checked the animals become poorer and poorer, and 

 die before long. 



By rubbing against posts and other objects many mites 

 and their eggs are removed, and thus frequently find lodg- 

 ment upon healthy sheep. The mites can readily be found, 

 but not in the early stages of the disease. 



Remedies. — "Whatever kills the mite cures the scab" may 

 be said to be the rule that we have to follow to exterminate 

 them. Internal remedies have no value vsrhatever, except in 

 cases where the animal infested is weak, and Vk^here rich food 

 is necessary to strengthen the patient. 



Creosote, solutions of potash, alkalies mixed with fat, 

 oil of turpentine, benzine, kerosene, tar, tobacco, hellebore, 

 mercury, and arsenic kill the mites more or less rapidly. 



Vogel made some experiments, under the microscope, 

 and found that scab-mites were killed as follows: 



Within one minute by creosote, carbolic soap and ben- 

 zine. 



Within several minutes by tar and caustic potash solu- 

 tions. 



Within one-quarter to one-half hour by tobacco or helle- 

 bore. 



Within one hour by soft soap. 



Within two hours by arsenic. 



Within four hours by corrosive sublimate. 



In Europe, where all flocks of sheep are given in charge 



