FASCiATION IN EVENING PRIMROSES. 147 



bers of the larvse of a small moth named Mompha, which sub- 

 sist on the pith toward the end of summer, and winter in the 

 hollow stem. Some of the larva? develop in the ovary and emerge 

 in the winged state from the ripened capsnle. Still others hatch 

 in the leaf v tip of the flowering stalk or in the rosette, and in the 

 latter bind together the leaves to make a protective covering and 

 feed in its heart during the cold months. In each case the eggs 

 are laid in the growing region, so that the initial meristem is 

 subject to injnrv from tlie ovipositor. In tlie last instance large 

 mutilations may be caused l>y the devastations of the feeding, 

 and sncli ravages account for the frequent abortion of the main 

 axis among tlie fasciated plants. On the other hand many 

 ]dants remain unaffected, for the new leaves furnish snfficient 

 food, the larva does not penetrate the center of the axis, and 

 never reaches the meristem. In still a third case the meristem 

 may be barely tonched or irritated, and the injury may be a 

 small one in its effects similar to tho'^e caused l)y the ovipositor. 

 AVhere the Avound is inflicted by the month parts of the larva it is 

 ordinarily more easily detected than when made by the ovipos- 

 itor of the imago, for 'it frequently interferes with procambial 

 development in snch a way tliat the l)undle ring is symmetrical, 

 or there is conspicuous callus formation, or other signs are evi- 

 dent, bv wliicli its course mav lie traced and its orio-in ascer- 

 tained. When the tissues are pierced by the ovi])ositor the in- 

 jury is so small that it is impossible to find it after any consider- 

 able amount of growth has occurred. A comparatively deep 

 incision measures 1.2r)mm in longitudinal section; it disap]iears 

 almost immediately u]ion the consequent enlargement of the sur- 

 rounding cells, and it is useless to look for traces of it at ad- 

 vanced stages of development. Fasciated tips so young that 

 their flattened character can. only be det(M'niiued microscopically 

 show wounds in the meriste.ms at the a]nces, but as the banding 

 of the stem becomes conspicuous, all traces of the disturbance are 

 gradually lost. 



The vouu"' fasciated tii)s can be recon'nized externallv liv their 

 compact appearance due to the abnormal numlier of leaves; by 



