The induction, development, and heritability of fasciations . and new swarms of imag-osbegin to emerg-e toward the end of the summer, at once proceeding- to sting-new tips. Those apices which have passed the period of greatest vig-orgradually dwindle away and die, but leafy axes, leafy rosettes, stems readyto flower through September, all soft tissues in a thriving- condition, thenfasciate in greater abundance proportionately than earlier in the season,for their limited number makes it more certain that they will be attackedby the recent-invasion of the new swarm. In the rosette stage the rate
The induction, development, and heritability of fasciations . and new swarms of imag-osbegin to emerg-e toward the end of the summer, at once proceeding- to sting-new tips. Those apices which have passed the period of greatest vig-orgradually dwindle away and die, but leafy axes, leafy rosettes, stems readyto flower through September, all soft tissues in a thriving- condition, thenfasciate in greater abundance proportionately than earlier in the season,for their limited number makes it more certain that they will be attackedby the recent-invasion of the new swarm. In the rosette stage the rate ofgrowth is also important. It is seldom that the insect reaches the apicalmeristem of-a quick-growing plant, for the rapid formation of new leavessupplies sufficient food for the larva, and the formative region remainsimtouched. Sections of numbers of young containing larvae easilyprove that the insect ordinarily feeds above the apex or at its side. Thoughplants are often unaftected by the parasites, doubtless swarms occasionally Knox Plate III. OENOTHERA CRUCIATA, I. Young protuberance. 2. Stung tip. 3. Oldprotuberance and bifurcation with one fasciated branch. 4. Protuberances asso-ciated with the flattening of the stem. 5. Protuberance surrounded by fascia-tions. 6. Early stage in the formation of a protuberance. INDUCTION, DEVELOPMENT, AND HERITABILITY OF FASCIATIONS. 13 develop whose month-parts are sharper than those of their fellows, or whosehabit it is to bore deep for the youngest and most tender food. In thesame way there are swarms of imag^os which have longer ovipositors, orwhich show a preference for the center of the apex rather than the axils ofthe embryonic flowers. If the character of the attacks of the insects varieswith the character of the insect swarm, this should account for the wide-spread appearance of fasciation over one restricted locality, while in adja-cent areas, beyond but insignificant barriers, no fasciated plants are found. The curio
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