676 MEDICAL ENTOMOLOGY 



The pressure causes the tick to spread out its legs, thus preventing them 

 from obscuring the view, as they do when curled up ; in many cases the 

 palps are separated, permitting a better view of the mandibles and hypos- 

 tome. To fix the tick in this position the slides are dropped into boiling 

 water or boiling seventy per cent alcohol, which kills it instantly and 

 without any alteration in position. The slides are placed in cold 

 seventy per cent alcohol in suitable glass tubes for twenty-four hours, 

 and the tick then removed ; in some cases it is necessary to place the 

 slides for a short time in absolute alcohol. The specimen is then 

 transferred to a small tube in fresh seventy per cent alcohol, taking care 

 to have a good cork. 



Ticks can be cleared by placing them in a two per cent solution of 



caustic potash in the cold ; the solution should be filtered before use and 



changed after forty-eight hours. A small nick should 



Ma specimen 8 * P6( invariably be made in the body in some unimportant site 

 so as to allow the potash to penetrate into the interior. 

 After the tick has been in the solution for four days it should be 

 gently compressed with a flat pair of forceps, when the dissolved internal 

 organs will exude as a yellow fluid. When the specimen is sufficiently 

 cleared this can only be learned by experience it should be washed in 

 running water for ten minutes, and then dehydrated by passing it through 

 graded alcohols up to absolute alcohol ; it should then be cleared in oil 

 of cloves for several hours and mounted in Canada balsam. If necessary, 

 the integument and other parts can be stained with a saturated solution 

 of carbol fuschine or Orange G, after washing and before dehydration. 

 The specimen may be mounted in any desired position either on a plane 

 or in a hollow slide. Larvae and nymphs should be treated in the same 

 way. Eggs may be preserved in the way described for the eggs of 

 Diptera (see page 417). 



Special structures may be mounted separately, after dissecting them 

 out while the tick is soft or when it is in the oil of cloves. In this way 

 the capitulum, the mandibles, hypostome, palps, legs, and spiracle may 

 be removed ; they make excellent mounted specimens. 



Ticks required for further experiment may be kept alive as follows : 

 Place them as they drop off the host in ordinary test tubes, the mouths 



. ^ . of which are plugged with cotton surrounded by thin 



Keeping of live ticks ' 



paper the paper prevents larvae from becoming 

 entangled in the wool. The tubes should be placed on their sides on a 

 cupboard, each with a label which corresponds with the entry in the 

 notebook in which all the details regarding each specimen are written. 



