16 
room for motion, succeed ill escaping from such a prison ? The rigid 
shell of the bird's egg is easily cracked by the beak of its tenant ; tbe 
batching caterpillar, curled within its eggshell, has room enough to 
move its jaws and eat its way out; the egg-coverings 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 mussel ; whilst in a host 
of others the embryon is furnished with a special structure called the 
egg-burster, the office of which is to cut or rupture the shell, aud 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 contrivances. 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 swellingof the embryon within. 
Thus, the eggs when about to hatch are much more plump and some- 
what larger and more transparent than they were when laid. At last, 
by the muscular efforts of the nascent locust, and the swelling 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 indi- 
viduals await the escape of those in front of them, which first push 
their way out through the neck of the burrow (PL I, Fig. 4, d) provided 
by the parent. 
They all escape, one after the other, through one small hole, which 
in the field is scarcely noticeable. Such is the usual mode of hatching ; 
but when the young from the lower eggs hatch first, or when the upper 
eggs perish and leave the lower ones sound — as is not unfrequeutty the 
case — the exit is nevertheless easily made along the channel already 
described (PI. I, Fig. 5, c). 
When once the shell is ruptured the nascent larva soon succeeds, by 
a series of uudulating movements, in working free therefrom aud mak- 
ing its way to the light in the manner just described. Once on the sur- 
face of the ground it rests for a few minutes, generally lying on the 
side. Its members are still limp and directed backward, and it is yet 
enveloped in a very delicate film or pellicle, which must be cast off be- 
fore the little creature can move with alacrity. 
By continuance of similar contracting and expanding movements 
which freed the animal from the earth, this film in a very short time 
splits along the middle of the back near the head (strictly the protho- 
