106 PREPARATION AND MOUNTING 



This method of preparing and mounting insects I cac 

 strongly recommend as giving first-rate results ; but where 

 the specimens are small, they seldom need the soaking in 

 caustic potash which larger ones must have. It is only 

 necessary to leave them awhile in turpentine, especially 

 when they have been first dried with gentle pressure between 

 two glasses, and then mount with balsam in the ordinary 

 way. With many, even of the larger insects, by soaking 

 them in turpentine or oil of cloves for a longer time, they 

 are made so much more transparent and even colourless, 

 as to exhibit their internal organs (which are visible in 

 layers, by the aid of the binocular microscope), the muscles 

 of the legs, &c. They become also very beautiful objects for 

 the polariscope. 



Amongst the insect tribes there is abundant employment, 

 especially for the lower powers of the microscope. But if 

 the deeper wonders and beauties of the animal economy 

 are to be sought out aad studied, it is desirable that the 

 various parts should be set separately, in order that they 

 may receive a more undivided attention, as well as be ren- 

 dered capable of being dealt with under the higher powers. 

 We will therefore briefly consider the treatment which the 

 different portions require. 



The eyes of butterflies, and indeed of almost all insects, 

 afford materials for a study which is complete in itself. 

 When examined with a tolerably high power, instead of 

 finding each eye with an unbroken spherical surface, it is 

 seen that many are composed of thousands of hexagonal 

 divisions, each being the outer surface of a separate portion 

 termed the ocellus. In others these divisions are square; 

 but in all there is a layer of dark pigment surrounding their 

 lower parts. The ocelli may be partly removed from tho 

 eye, which will show how their tapering forms are arranged. 

 But here we have to consider how to place them in balsam 

 for preservation. The eye being removed from the insect, 

 and the dark pigment removed by the use of a camel-hair 

 pencil, must be allowed to remain in turpentine at least for 



