10 IXnUCTIOX, DKVnLOPMEXT, AND II I< RITABI LITV OF FASCIATIOXS. 



precedes a ring'-fasciation, though as yet no ring-fasciation was apparent. 

 In all wild (>. lucimis the stems were infested with larvae below the fasciations 

 and the grooves full of callus, yet it was impossible to find intermediate 

 conditions. A plant with a fresh larval trail up the side faseiated after a 

 month of elongation from the rosette stage, but by the time the character 

 of the tip was \vell determined the first effects were obscured by the later 

 growth. Unequal formation of wood on the two sides at the base of fas- 

 eiated stems may be taken as an indication of local inhibition. Transverse 

 sections of the lower, round part of branches, which are fiat above, usually 

 reveal variations in the width of the woody ring. The difference may be 

 slight or, in a few cases, as in plate v, fig. 16, very marked and accom- 

 panied by callus formation. In the groove -fasciations (plate iv, figs. l/>, 

 \l>) the width of the primary wood where it adjoins the groove, at xx, is 

 narrower than at.rr. This is also found to be true in sectioning the rosettes 

 cut in late summer from the old stems (plate v, fig. 9). 



What has been said applies to plants out of doors. It seemed probable 

 that a different state of things would hold in the greenhouse. Vet the 

 faseiated rosettes in the greenhouse have in the stems circular meristems 

 about brownish discolorations and a significant feature of their development 

 is one-sidedness of growth and a forcing out of the axillary branches. 

 Rosettes of O. cntciata planted June 16, 1906, and kept in the greenhouse 

 during the summer, were subject to such conditions in the pith. These, 

 like the rosettes of (). pa rv if/ or a of 1905-1906, showed rough places on the 

 petioles and midribs of the leaves, incurling of some of the leaves in the 

 growing tip, and ruffling of the margins. The O. parrif/ora planted in 

 the summer of 1905, in December, showed larger and longer leaves on one 

 side than on the other. There was then no sign of linear growth, but in 

 April they began to fasciatc, and in May all four plants were faseiated. 

 1'Yequently the rosettes tip up, owing to the premature development of a 

 lateral branch (plate n, fig. 4), so that one side is higher than the other. 

 This looks as if there were inhibition of growth on the concave surface. 

 The result of further growth is often a complete torsion of the faseiated 

 main axis with fasciation also in the side branches. In studying fasciation, 

 species with compact symmetrical rosettes are much to be preferred. O. 

 i'raiulillora is among the impracticable forms, for the side branches normally 

 come out very early. A double rosette of l\aiiucainia odor^Ui, a near relative 

 of the oenotheras, the plant illustrated in text fig. 1 and in plate v, fig. 17, 

 when sectioned was found to have been injured below the bifurcation, and 

 at this point (.\ r) there was inhibition in the formation of wood. Only the 

 bifurcated fasciations can be detected at the start, and these are of com- 

 paratively rare- occurrence. It is evident, however, that the rosettes under 

 cover are not exempt from outside injury, and insects may readily enter the 

 greenhouse through the open ventilators, besides the many which habitually 

 live there. 



