BY C. J. POUND, F.R.M.S. 33 



LIFE HISTORY. 



To complete its life history the tick, like almost all insects, 

 has to undergo four distinct changes, technically known as 

 metamorphoses — first, the egg; second, the larva; third the 

 pupa or nymph ; and fourth, or last stage, the sexually mature 

 adult. 



After due consideration I have deemed it advisable to com - 

 mence by describing the process of oviposition or egg-laying, and 

 the changes occasioned thereby in the female tick. 



If we remove a number of fully -developed female ticks fi-om 

 ■a beast and place them in a small covered dish, we notice from 

 day to day various obvious changes taking place. First of all, 

 the fully developed female tick is somewhere about the shape and 

 size of the seed of the castor oil plant ; as a rule the ventral or 

 underneath parts are of a dull leaden or bluish colour, while the 

 dorsum or back of the tick has a slightly dull greenish hue. 

 Under favourable circumstance in a few days several irregular 

 yellow marks make their appearance all over the body. Tbese 

 gradually increase in size, and indicate that at an early daw the 

 €gg-laying process will commence. 



I need hardly mention that this process of oviposition, wbich 

 was first of all carefully worked out some eight years ago in Lon- 

 don by my friend Mr. R. T. Lewis, of the Quekett Microscopical 

 Society, is a most interesting and fascinating study for the 

 microscopist. To the unaided eye it appears as though the eggs 

 were ejected direct from the mouth itself, whereas the microscope 

 reveals the fact that the ovipositor, or termination of the little 

 duct down which the egg passes from the ovaries, is situated 

 immediately behind the mouth organs, which, however, assist 

 mechanically during the process of oviposition. P)y means of 

 the microscope I have watched for hours together on different 

 occasions this interesting process, and I must admit that each 

 time I elicited further information. 



The first indication that an egg is about to be laid is the 

 continued, peculiarly slow waving movement of the anterior pair 

 of legs, which are invariably turned in an upward direction ; 

 then the ovipositor, which is retractile, is pushed forward ; also a 

 membraneous sac makes its appearance just above the palpi, 



