INDUCTION, DEVELOPMENT, AND HERITABILITV OF FASCIATIONS. 13 



develop whose mouth-parts are sharper than those of their fellows, or whose 

 habit it is to bore deep for the youngest and most tender food. In the 

 same way there are swarms of imagos which have longer ovipositors, or 

 which show a preference for the center of the apex rather than the axils of 

 the embryonic flowers. If the character of the attacks of the insects varies 

 with 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 "curious" habit of fasciated stems in that those of annuals are at 

 first round and later flatten, while those of biennials originate large and flat 

 and stay so, has been noted by de Vries (ll). In the primroses under 

 observation this seems to be accounted for by the state of development at 

 the time of the sting of the insect. In the cultures of O. fiarvi flora rosettes 

 planted in the summer of 1905, and kept over, fasciated during the winter; 

 those sown in February elongated quickly after being placed out and fas- 

 ciated in the upper parts of the branches. Two plants of the February 

 sowing, which grew more slowly than the others, were fasciated rosettes in 

 September. In general, plants or branches which were in the rosette stage 

 in July and August, or at the time when the insects were laying their eggs 

 and the larvae were hatching, fasciated as rosettes and produced flat stems 

 the following season. Plants in the flowering state during the same period 

 fasciated in the upper part of the stems. Plants elongating from the 

 rosette stage in September fasciated comparatively low down on the stem as 

 in plate in, fig. 6. Any plant, moreover, may fasciate in its rosette stage 

 the first season, and in the upper part of its side branches the second 

 season. To secure the most striking results in New York, seed should be 

 planted in April or May and allowed to remain out of doors in the rosette 

 stage through the summer. Plants from seed sown in February begin to 

 elongate too early to show linear growth long before the flowering tips are 

 ripe. So many of the wild plants are aborted in the main axis that one 

 may assume that the tip is eaten off by larvae soon after the plant elongates 

 from the rosette stage. Among the wild plants there were many larvae 

 in the field in June in the young shoots. The side-branches are doubtless 

 injured as they are forced out, for the callus in the grooves of some of the 

 branches and in the lower parts of the cavity of the rings in others indicates 

 early effects of injury in these secondary branches. 



The conditions of culture, as has been already stated, were favorable to 

 the vigorous growth of the garden plants. Individuals were from 2 to 4 

 feet apart and were well-fertilized and watered. The interesting experi- 

 ments of de Vries and of Hus (22) at the Missouri Botanical Garden sug- 

 gest that if some of the unfasciated plants had been subjected to different 

 conditions they too might have fasciated. It is possible, also, that if the 

 plants had been planted in April instead of in February the result might 

 have been different. The environment must, however, be suited to the 



