The reproductive individuals have undergone an extraordinary simplification of the organs concerned with the collection and digestion of food.
The reproductive organs do not begin to appear until the larva has twice cast its skin.
In subsequent generations produced by self-fertilization of the hybrids it was found that the positive character was not present in all the individuals, but that a result was obtained showing that in the formation of the reproductive cells (ova and sperms) of the hybrid, half were endowed with the positive character and half with the negative.
Insect metamorphosis may be briefly described as phenomena of development characterized by abrupt changes of appearance and of structure, occurring during the period subsequent to embryonic development and antecedent to the reproductive state.
Reproductive organs with ducts leading to the vestibule.