G2 



Arizona that I, for a time, considered this the normal condition 

 of the plant. In all cases observed the fruit-joint is small, very 

 uniform and regular and has the same form as the normal joint. 

 In 1903 a single plant of this variety in the Celero Mountains 

 produced 18 of these fruit-joint structures and no normal fruits. 

 In 1905 the same plant produced not less than 50 perfectly 

 normal fruits with no abnormals. These were carefully exam- 

 ined but no insect or other injury was found to which the condi- 

 tion could be attributed, but I am inclined to look for some 

 mechanical explanation for the phenomenon. This is the only 

 species in which regular abnormal structures of this kind have 

 been observed. Usually the fruit simpl)- appears to expand on 

 one side or the other into a joint-like structure with no regularity 

 or symmetry. Such abnormalities are very common in the 

 Mexican cultivated forms such as Nopal aniarillo, uaraiic/iado, 

 cmnitcso, tcco, etc. 



A very peculiar set of fruit modifications is brought about by 

 insect depredations. A dipterous insect which deposits its egg 

 in the ovary of 0. Liiidhciuicri invariably causes a reversion to 

 the vegetative condition. The ovules become atrophied, the 

 funiculi (?) developing into short, c)'lindrical, curved and twisted 

 structures and the ovary remaining green. So far does the ovary 

 change to the vegetative condition that it very commonly gives 

 rise to joints so that we have joints developing from imperfect 

 but good-sized fruits. Such growths have been very common 

 in southern Texas for the past two years. Such structures, how- 

 ever, are never incorporated as a permanent part of the plant in 

 this species but drop off early the following summer after the 

 insects have matured. 



A similar (possibly the same) insect affects the ovaries of 0- 

 versicolor in much the same way but the gro.wth of joints from 

 the ovaries is somewhat rare. Frequently in this, less frequently 

 in 0. Liiidlicimeri and commonly in other Cylindropuntias there 

 is a tendency for the pistil to begin a reversion into the vege- 

 tative state and remain, so far as its hollow base is concerned, 

 upon the ovary until the latter drops off of the plant. In some 

 cases the base of the pistil actually enlarges slightly, /. c, starts 



