PROCURING OBJECTS. 87 



objects for examination, as there is scarcely a part of the body 

 of an insect that does not exhibit some remarkable structure. 



Antennae. The horns of insects not only vary in form in 

 different genera, but in the male and female of the same 

 species. They may be mounted as opaque, or in Canada 

 balsam. 



Eggs. The eggs of insects are generally of an oval form, 

 the outer covering being sufficiently rigid to resist ordinary 

 external impressions ; others are, however, soft and pliant. In 

 some species they are globose, as in many Lepidoptera ; or 

 conical, as in the large white cabbage-butterfly; cylindrical, 

 pear-shaped, barrel-shaped, &c. They are for the most part 

 smooth ; but many are very beautiful, ornamented with symme- 

 trical ridges, canals, dots, &c., giving them, as Reaumer ob- 

 served, the appearance of embossed buttons. Some are fur- 

 nished with appendages for peculiar purposes. Thus the eggs 

 of the dung-fly (Scatophaga putris) has two oblique props at 

 one end, to prevent it sinking too deep in the matter upon 

 which it is deposited, while those of the water-scorpion (Nepa 

 cinerea) are furnished with a coronet of spines, forming a re- 

 ceptacle for the egg which is deposited immediately after- 

 wards. Sometimes, one end of the egg is provided with a 

 sort of cap or lid; at other times the egg is in one piece, and 

 the enclosed larva must gnaw or burst through it. The color 

 is very various, although white, yellow, and green are the 

 most prevalent tints. 



In many species the eggs are deposited singly ; in others, 

 they are discharged en masse. Some arrange them symme- 

 trically, and others enclose them in a mass of gluten, espe- 

 cially those whose larvae inhabit the water. Many species em- 

 ploy a gummy matter to attach them firmly to the substances 

 on which they are placed ; while some, as the yellow-tail moth 

 (Arctia chrysorrhaea), wrap them in a coating of down, which 



