216 The Journal 
staminate, or malés, and therefore use- 
less, only a few trees being necessary 
to pollinate all the pistillate trees. It 
is impossible so far to distinguish the 
staminate from the pistillate trees in 
the early stages of their development. 
Therefore, in any papaya orchard 
planted with the dioecious type, a very 
large percentage of the trees must be 
cut out after they have grown almost 
to maturity, resulting in unevenness and 
irregularity in the orchard and much 
loss of time and space. For this reason, 
together with the difficulties of breed- 
ing, the dioecious type probably will be 
largely eliminated. 
BREEDING HERMAPHRODITE FORMS 
Turning to the hermaphrodite forms 
with more hope of results, we find that 
a number of experiments are being con- 
ducted. Here it is possible to deal with 
a single individual mother plant. One 
of the first facts to be determined is the 
extent to which the offspring of such a 
parent may be expected to be fruit- 
bearing trees. It was known from 
earlier observation, without any def- 
inite experiment, that a large number 
of the seeds from a fruit of a herma- 
phrodite flower produce fruit-bearing 
trees, either pistillate or, like the 
parent, hermaphrodite. 
A tree was found in a Honolulu 
orchard producing fruit of excellent 
flavor. The fruit from which the seed 
was taken was of the long cylindrical 
form, but it cannot be stated that all 
the fruits on the tree were of that shape. 
Its flowers were apparently staminate 
and hermaphrodite, and so far as ob- 
served, of the Elongata form, but it is 
probable that the apparently staminate 
flowers were non-functioning. The 
flowers had not been hand-pollinated, 
and it is therefore impossible to state 
whether they were self-fertilized or 
otherwise. The seeds were planted 
May 2, 1910, and later thirty-five of 
the young plants were set in the orchard. 
Of these, thirty-four were hermaphro- 
dite and one was a staminate tree. The 
hermaphrodite flowers on most of the 
trees were of two types, some of the 
Elongata form and others resembling 
Pentandria, with corresponding differ- 
of Heredity 
ence in the fruits. The best one of the 
trees from the standpoint of uniformity 
of cylindrical shape in fruit was also of 
very good flavor and a reasonably good 
producer; it was selected for further 
breeding. Two of its flowers were hand- 
pollinated each with its own pollen and 
carefully protected. The seeds collected 
from these two fruits were planted, and 
it was found that 94% of the result- 
ing trees were fruit-bearing, being either 
pi tillate or some form of hermaphrodite. 
This is an encouraging result, so far 
as the elimination of the males is con- 
cerned. It is probable that by the 
continued use of hermaphrodites of the 
Elongata form as a source of pollen 
as well as for the pistil-bearing parent, 
male forms may be largely eliminated. 
CROSSING THE DIFFERENT FORMS 
It has been found possible to cross 
quite freely most of the different forms 
of the papaya, as would be expected 
from the fact that they all are merely 
slight modifications of the same species. 
Among the experiments now in progress 
is one to determine the sex resultants 
arising from the crossing of a pistillate 
of dioecious origin with pollen from a 
hermaphrodite. If, as is expected, the 
progeny will be chiefly pistillate and 
hermaphrodite, then desired characters 
that may be found in any dioecious 
stocks may be combined with herma- 
phrodite stock. 
Like other tropical fruits, the papaya 
still offers an almost virgin field to the 
plant breeder. But enough has been 
done to make it certain, I think, that 
a strain can be established which, com- 
bining the two sexes on the same tree, 
will produce from seed a desirable fruit, 
without the production of a great many 
useless male trees. 
The successful achievement of this 
task, and the dissemination of the 
resulting strain, will give a tremendous 
impetus to the culture of the papaya, 
But there is still another possible field 
of work—namely, crossing with other 
species. 
It is probable that there has been 
considerable hybridizing of Carica by 
natural means, and breeders have not 
wholly neglected the genus. I will not 
