40 



Development and Metamorphosis 



men to the water's surface, there releasing them, or even crawling clown 

 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- 



FlG. 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, embrjo 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; scr., serosa; am., amnion; ant,, antenna; lb., labrum; 

 md., mandible; mx., maxilla; m.v.p., maxillary palpus; //., labium; li.p., labial 

 palpus; /', P, P, legs; pr., proctodeum, 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 carrictl their developmental course in the egg, 

 latch either almost wholly like their j)arents (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 



