Natural History and Transformations . 75 



of many insects are so delicate and frail that the mere 

 swelling of the embryon affords means of escape ; those 

 of others are so constructed that a door flies open, or a lid 

 lifts by a spring, whenever pressure is brought to bear : 

 in some, two halves open, as in the shell of a muscle ; 

 whilst in a host of others the embryon is furnished with a 

 special structure, called the egg-burster,* the ofhce of 

 which is to cut or rupture the shell, and thus afford means 

 of escape. But our young locust is deprived of all such 

 contrivances, and must have another mode of exit from 

 its tough and sub-elastic prison. Nature accomplishes the 

 same end in many different ways. She is rich in contriv- 

 ances. The same warmth and moisture which promote 

 the development of the living embryon, also weaken the 

 inanimate shell, by a process analogous to decomposition, 

 and by a general expansion consequent upon the swelling 

 of the embryon within. Thus, the eggs when about to 

 hatch are much more plump and somewhat larger and 

 more transparent than they were when laid. At last, by 

 the muscular efforts of the nascent locust, and the swell- 

 ing of its several parts, especially about the head and 

 mouth, the shell gives way, generally splitting along the 

 anterior ventral part. The whole process may, in fact, be 

 likened to the germination of a hard-covered seed, when 

 planted in moist ground, and, precisely as in this latter 

 case, there is, in some loose soils, a certain heaving of the 

 ground, from the united swelling of the locust eggs. All 

 the eggs in a given mass burst very nearly at one and the 

 same time, and in that event the lowermost individuals 

 await the escape of those in front of them, which first 

 push their way out through the neck of the burrow (Fig. 

 9, d,) provided by the parent. 



* 1 have elsewhere (Mo. Ent. Kep. 9, p 127,) called this the Euptor ovi. 



