61 



and the young parasite emerges in due time. They are then subjected 

 to a second dip some six or ten days afterwards, at which time it is pre- 

 sumable that all the eggs have hatched and none of the young have be- 

 come adult. If the second dip is delayed much longer than twelve or 

 fourteen days, some of the newly hatched larvai may have become adult 

 and laid eggs, which may in turn hatch larvae, and become new centers 

 of infection. 



All dips, to be effective, contain some ingredients which are poisonous 

 to t;he parasite. This poisonous element may also, if used in too con- 

 centrated a solution, be poisonous to the sheep, but this is to be avoided 

 by using the dips in the exact proportions of the formula given and 

 maintaining these proportions throughout the treatment. In addition 

 to the poisonous element, a dip may contain other elements, as water to 

 dissolve and to dilute the poison ; also such a substance as alum or soda 

 to combine with the poison, as arsenic, to make it more soluble ; or it 

 may contain an alkali, as soda or potash, to soften the scabs <vhen ap- 

 plied ; or it may contain substances which are empirically added because 

 they have been experimentally proven of service. 



The chief poisons used in the dip are tobacco, arsenic, and carbolic 

 acid. Of these, tobacco is the favorite, because its use has not been 

 followed by the fatality that has in times past followed the use of 

 arsenic. Carbolic acid is too expensive to be used in large quantities, 

 but is an excellent ingredient when only a few sheep are to be dipped. 



The addition of tar to these dips is excellent, as the tar water is not 

 only good for the wounds but serves an excellent purpose of driving 

 away the flies. 



The quantity of dip required for each sheep is variously estimated at 

 from 1 quart to 1 gallon. For small numbers of sheep, say fifty or one 

 hundred, the larger amount is necessary, but for large flocks, 1 quart 

 for shorn and 2 for unshorn sheep may be allowed. It is always best 

 to have more of the ingredients on hand than is necessary, so that they 

 may not be used up before the dipping is finished and thus delay the 

 business. To make the dip more effective the solution should be ad- 

 nrinistered quite hot. The most desirable temperature is from 100° to 

 110° Pah., which is a comfortable one for the sheep, whose internal 

 temperature is about 103°. The warmth enables the dip to penetrate 

 the oily wool better, makes the parasites livelier, and proves far more 

 efficient. 



Instead of treating the scab by one application some authorities ad- 

 vise the use of a preliminary dip of alkaline water to soften the scabs, 

 or of oil or glycerine well rubbed in for the same purpose. This is to be 

 followed in two or three days by a poisonous dip. Nearly all advise 

 that the scabs should be rubbed with a stiff brush while the sheep is 

 being dipped. 



The Australian or Eutherford dip, which has been very successful in 

 the hands of large flockmasters, is as follows : Take of tobacco and 



