652 MEDICAL ENTOMOLOGY 



trough described in Chapter XI is very convenient for ticks, but if one 

 is not available a large watch-glass in which some dark plasticine has been 

 moulded will answer the purpose. The trough should be three-quarters 

 filled with saline solution. 



The anterior part of the body of the tick is grasped between the thumb 

 and fore finger of the left hand, and a thin slice of the posterior edge of 

 the integument is cut off with one sweep of a fine pair of scissors ; the 

 cut should commence about the level of leg IV on the left side the dorsal 

 surface being uppermost and is carried rapidly as far round to the 

 other side as possible. If the specimen is much distended a pair of 

 flat entomological forceps may be used instead of the fingers ; they should 

 be placed about the level of the anus, in order to press as much of the 

 contents of the abdomen as possible towards the anterior end, so that 

 they will net protrude when the cut is made. Even with a partially 

 fed tick the ends of one or more of the diverticula almost invariably 

 rupture, but if undue pressure is avoided only a small quantity of the 

 contents exude and the specimen is in no way spoiled. The tick is 

 now dropped into the saline solution in the trough and is arranged so 

 that its dorsal surface is uppermost. If a species of Ixodinae has been 

 selected a No. 20 entomological pin is passed through one side of the 

 basis capituli, and the specimen is fixed firmly to the wax by bending 

 the pin over ; if the tick is a species of Argas or Ornithodorns, the pin 

 should be passed through the fold of skin at the anterior edge. The 

 trough is placed on the stage of a binocular dissecting microscope 

 and the lowest pair of objectives used. The dorsal integument at the 

 site of the cut is grasped with a pair of fine forceps held in the left 

 hand, and with a dissecting needle in the right hand the ventral integu- 

 ment is pressed against the wax of the trough ; the two portions of skin 

 are now gently separated and one or more pins are -passed through the 

 ventral skin to fix it to the wax. The dorsal integument can be reflected 

 up to the point where the cut ended ; a needle with a cutting edge is 

 then passed between the two surfaces, great care being taken not to 

 damage the intestine, and a series of lateral cuts is made ; in this way 

 the dorsal skin is completely separated up to the anterior end, and it 

 can be reflected and pinned down. The internal organs are now exposed. 

 In the case of the Ixodinae it is important to remember that the skin 

 readily tears away from the scutum, and that when this is reached, 

 in the dissection of a female, only very slight traction should be 

 applied. 



As the dorsal integument is reflected off it will be found to be bound 



