DISEASES OF SHEEP 541 



need not be considered; on long wool the injury is greater and seems 

 to vary with different wools, being greater on a fine than on a coarse 

 wool. This injury consists chiefly in a change in the microscopic 

 structure of the fiber, caused by the caustic action of the ooze. When 

 improperly made and improperly used the lime-and-sulphur dips 

 are both injurious and dangerous, and in these cases the cheapness 

 of the ingredients does not justify their use. In case scab exists in a 

 flock and the farmer wishes to eradicate it, he can not choose a dip 

 which will bring about a more thorough cure than will lime and 

 sulphur (properly made and properly used), although it will be 

 perfectly possible for the farmer to find several other dips which 

 will, when properly used, be nearly or equally as effectual as any 

 lime-and-sulphur dip. There is no dip to which objections can not 

 be raised. 



Tobacco Dips. The active principle of tobacco, upon which 

 the tobacco dips depend for their action, is a poisonous substance 

 known as nicotine. This poison when applied to animals externally 

 in too strong solutions may cause nausea, fainting, and even death. 

 The dog and the rabbit are particularly susceptible to its effects. 

 Diluted to about thirty-three one-thousandths to sixty one-thou- 

 sandths of 1 per cent it makes a slow but sure-acting and excellent 

 sheep dip. 



Unfortunately the percentage of nicotine varies greatly, not 

 only in different kinds of tobacco, but also in different parts of the 

 plant, in different years, and even in different parts of the same 

 package. There is more nicotine in the leaves, for instance, than in 

 the stems. 



On account of the variation in the amount of nicotine in the 

 different samples of tobacco, it is practically impossible for the 

 farmer to make up an exact desired strength of tobacco dip if he 

 prepares his own mixture from the leaves. He can, however, pre- 

 pare a mixture which will come within the limits suited to kill the 

 scab parasites. If a solution of an exact given strength is desired, it 

 will be necessary to buy prepared nicotine, or prepared tobacco dips 

 of a guaranteed strength, and reduce them to the strength deter- 

 mined upon. 



Directions for Preparing the Dip. For every 100 gallons of 

 dip desired, take 21 pounds of good prepared tobacco leaves; soak 

 the leaves in cold or lukewarm water for twenty-four hours in a cov- 

 ered pot or kettle ; then bring the water to near the boiling point for 

 a moment, and, if in the morning, allow the infusion to draw for an 

 hour; if in the evening, allow it to draw over night; the liquid is 

 next strained (pressure being used to extract as much nicotine as 

 possible from the wet leaves) and diluted to 100 gallons per 21 

 pounds of tobacco. This dip should be used as fresh as possible, as 

 it contains a large amount of organic material which will soon de- 

 compose. 



The proportions here given 21 pounds of prepared tobacco 

 leaves to 100 gallons of water have given very satisfactory results, 

 especially in Cape Town colony, where the reports of the scab in- 



