650 MEDICAL ENTOMOLOGY 



behind the jaws with one hand, while with the other a firm hold is taken 

 of the tail. A snake held in this way is powerless, and can be examined for 

 ticks. .If this manoeuvre is carried out rapidly the snake is caught before 

 it. has realized what is happening. Sometimes, however, it is not caught 

 at once and then endeavours to escape ; in this case it should be followed 

 up and the flat end of the stick placed firmly on its head. The impor- 

 tant point to remember in catching snakes in this way is to act with 

 rapidity and never to hesitate; most snakes, even cobras and Russel's 

 vipers, are stunned for the moment when they are tipped out of the jar, 

 and it is at this moment that one should act. The two species of sand 

 snakes (Eryx johni and Gongliophns conicus) both of which often harbour 

 ticks, are the easiest to handle and can be kept alive for long periods in 

 captivity. 



If the snake is found to be harbouring ticks it should be placed in 

 a wire cage ; the one figured on Plate LXXXII, fig. 7 consists of three 

 compartments, and the meshes of the wire are just small enough to 

 prevent the snake from squeezing itself through ; most snakes make 

 vigorous attempts to escape. The cage is surrounded by a bag into 

 which the ticks fall when they leave the snake. Cobras are fed by 

 giving them egg beaten up with milk through a glass funnel passed 

 into the mouth; vipers will eat rats and frogs if placed in the cage ; 

 the rat snake, Zamenis mucosus, will readily eat frogs and toads. Sand 

 snakes may be fed on small lizards. 



.If the worker has a dead snake or lizard brought to him and finds it 

 has a number of ticks on it, he should on no account attempt to remove 

 them with forceps, as they are sure to be damaged. It is best to place 

 the snake in a white cloth bag for two or three hours, at the end of which 

 time all the ticks will have left the host and will be found crawling about 

 the bag. 



Before concluding this section some general points connected with tick 

 experiments may be mentioned : 



1. Unless for some special reason, large numbers of ticks should 

 never be placed on one host ; they only irritate the animal, causing it to 

 scratch them off, and may even in the case of small mammals and birds 

 cause death from loss of blood. A definite number should always be 

 used and those which have become attached noted ; ticks often wander 

 from the place where they first fixed themselves and select another site. 

 In some cases, however, it is necessary to place a large number on ah 

 animal in order to be certain that it will become infected with some parti- 

 cular protozoal parasite. For instance, only a small percentage of the 



