10 INDUCTION, DEVELOPMENT, AND HERITABILITY OF FASCIATIONS. 



precedes a ring'-fasciation, thoug'h as yet no ring"-fasciation was apparent. 

 In all wild O. bienuis the stems were infested with larvae below the faseiations 

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

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

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

 of the tip was well determined the first effects were obscured by the later 

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

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

 sections of tlie lower, round part of brandies, which are flat 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-fasciatkms (plate iv, fig's. I/', 

 4/>) the width of the primary wood where it adjoins the groove, at .v.v, is 

 narrower than at IT. 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. Yet the 

 fasciated 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. critcialu 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 O. />nr;'///oni of 1905-1906, showed roug'h 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. f>arrifiora 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 fasciate, and in May all four plants were fasciated. 

 Frequently the rosettes tip up, owing" to the premature development of a 

 lateral branch (plate n, tig". 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 fasciated 

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

 species with compact symmetrical rosettes are much to be preferred. (?. 

 ^randijlora is among" the impracticable forms, for the side branches normally 

 come out very early. A double rosette of Raimatuiia odorata, a near relative 

 of the (L-notheras, 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 (.v.v) there was inhibition in the formation of wood. Only the 

 bifurcated faseiations 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 througti the open ventilators, besides the many which habitually 

 live there. 



