27 
question may then be raised as to whether this potentiality to change 
exists in all parts of the plant at the supposed seasons of susceptibility 
or whether these stages of development are registered in the different 
parts of the plant as they are developed, in a manner like bud varia- 
tions. Nearly all the buds in the upper part of the papaya tree, 
except the terminal, remain dormant unless some injury occurs to 
the latter. If these possibilities to change exist as bud variations 
and it be necessary only to force the buds into growth in order to 
bring the differences into evidence, then it would follow that, while 
the removal of the terminal bud at different seasons might produce 
results, or not, according to the character of the buds immediately 
below, the cutting at some point lower down might bring about the 
change. An explanation of these phenomena on the basis of bud 
variation, however, need not presuppose a cyclic development or the 
possibility of changing all male trees. There is no lack of evidence 
that some of the unit characters of a hybrid may become separated in 
different parts of the plant. A hibiscus hybrid in the experiment 
gardens of this station produces flowers of different form and coloring 
on each of several main branches. It is well known that peach trees 
occasionally produce nectarines. But it is not necessary here to 
multiply instances of bud variation of which probably no better 
explanation has been offered than that they represent a character of 
some antecedent. Whether the facts of changing sex as presented 
are to be explained on a bud variation hypothesis is a matter of specu- 
lation, but the suggestion is made as one perhaps worthy of consid- 
eration in seeking a cause of the known facts. 
Whatever theories may be entertained as to the causes of the phe- 
nomena of changing sex, it still must be admitted that no practical 
and reliable method is at present available for converting a male tree 
to one bearing fruit. 
THE FEMALE IN SEX CHANGE. 
It is worthy of note that no record has been found by the writers, 
in the literature of the papaya, which would indicate that the female 
or pistillate tree has ever changed its sex. There are numerous 
reports of so-called "female" trees bearing hermaphrodite flowers or 
staminate, but this is apparently an inaccuracy in language, since in 
such cases no statement is made that a tree once purely pistillate in 
character has changed to one bearing other kinds of flowers. As has 
already been pointed out, there are forms with pistillate and other 
flowers mixed, and these have often been termed in a general but 
incorrect way ''female trees/' but such, so far as the records show,, 
have been the same in character throughout their existence. 
