4° 
Development and Metamorphosis 
men to the water’s surface, there releasing them, or even crawling down 
some water-plant beneath the surface and with arduous labor thrusting the 
eggs into the heart of this submerged plant-stem. From the eggs hatch 
wingless dwarf-dragons of the pond bottom, with terrible extensile, clutch¬ 
ing mouth-parts and an insatiable hunger for living prey. 
So our young insects, after completing their embryonic development, 
come to the time of their appearance as free individuals compelled to find 
their own food and no longer sheltered by a firm egg-shell from the strenu- 
Fig. 70.—Series of stages in development of egg of fish-moth, Lepisma sp. A, begin¬ 
ning embryo; B, embryo showing segmentation; C, embryo showing appendages; 
D, embryo more advanced; E , embryo still more advanced; F, embryo still older 
and removed from egg; G, embryo removed from egg at time of readiness to hatch. 
y., yolk; emb., embryo; ser ., serosa; am., amnion; ant., antenna; lb., labrum; 
md., mandible; mx., maxilla; mx.p., maxillary palpus; li., labium; li.p., labial 
palpus; l l , l 2 , P, legs; pr., proctodaeum, or intestinal invagination; cer., cerci; mp., 
middle posterior process. (After Heymons; greatly magnified.) 
ous fighting and hiding of the open road. Now these young insects, depend¬ 
ing upon how far they have carried their developmental course in the egg, 
hatch either almost wholly like their parents (excepting always in size), or 
in a condition fairly resembling the parents, but lacking all traces of wings 
and showing other less conspicuous dissimilarities, or finally they may appear 
in guise wholly unlike that of their parents, in such a condition indeed that 
they would not be recognized as insects of the same kind as the parents. 
But in all cases the young are certain, if they live their allotted days or weeks 
