PROLIFERATION. 



15 



1oe used in support of their position by the adherents 

 •of the theory that the pome consists solely of axial 

 tissue.* In cases of this sort, both in the pear and 

 -cucumber, the number of sepals may be more than five : 

 this number occurring at the top and one or more at a 

 lower level. 



In many ovaries with axile placentation it is probable 

 that the central part of the placenta is of axial nature, 

 representing an extension upwards, between the united 

 margins of the carpels, of the floral axis. That such 

 an extension may take place is proved, in certain plants, 

 by some abnormalities. For example, in the seedless 

 navel orange the axis is extended through the centre 

 of the fruit and forms a second complete (as regards 

 ■external conformation) but tiny orange at the top ; as 

 a rule this only partially projects beyond the rind of 

 the parent, and is sometimes split up, or partially so, 

 into its component carpels, just as we have seen that 

 the pear-fruit may become partially split up into its 

 constituent sepal-bases under similar circumstances. 

 This second orange bears, of course, no seeds. In 

 another orange of a different variety a small com- 

 plete fruit was observed entirely enclosed within the 

 parent ; it had a perfect rind. Immediately below the 

 small orange and closely appressed to it were some 

 structures having the appearance of a second whorl of 

 separate carpels. 



The most elementary type of proliferation of the 

 flower is afforded by those cases where the normally 

 cyclic flower becomes in greater or less degree acyclic, 

 the axis becoming abnormally elongated, and sometimes 

 spirally twisted ; good instances of this are the wheat- 



# The fact that this lateral sepal frequently produces an axillary "bud 

 (which in its turn may produce a second, pear) does not necessarily imply 

 that a cupular axis is present, for with Celakovsky it is best to maintain 

 that all axillary shoots are really adventitious on leaf-bases, and appear to 

 be readily formed where leaf-structures make an angle with the organ to 

 which they are attached, as in the case of leaf-segments of the tomato. On 

 these lines can also be explained the abnormal cucumber-fruits described 

 and figured by Masters which showed lateral proliferation ; for here the 

 lateral flowers probably arose in the axils of similarly displaced sepals, the 

 fruit being of the same morphological nature as that of a pear. 



