ON COLLECTING, PREPARATION, AND MOUNTING. 387 



&c. In the case of all insects which suck the juices from the food- 

 plant, as contrasted with those which eat the vegetable direct, it is 

 obvious that the vegetable cellular structure must be ruptured, and 

 therefore many disease spores may thus find a ready entrance into a 

 favourable host. Hence the obvious necessity of careful investigation 

 in many diseases, and the incalculable value of trained laboratory 

 research work. 



Such are a few " hints '' to the student from the writer's point of 

 view ; but it is possible that even advanced enthusiastic students ]nay 

 show a greater desire for life-histories than minute investigation. 

 Hence fig. 352 may be taken as a typical case of the life-history of an 

 insect, inasmuch as we see the successive stages of larval develop- 

 ment. In the example given we have, of course, an excellent instance 

 of the correct method for cabinet purposes ; but in reality all insects 

 should be worked out on similar lines, and the various stages noted 

 and tabulated in a book kept for the purpose. 



