14 
BULLETIN 61, HAWAII EXPERIMENT STATION 
previous to 1920 show that the so-called "male fruit" from the 
staminate plants of dioecious form will also produce monoecious 
and polygamous plants. This has led to the belief that the long- 
fruited monoecious and polygamous forms originated from these 
plants. Plants of these same sex forms have also developed from the 
seed of the purely pistillate dioecious form. 
During the past eight years efforts have been made at the station to 
improve the dioecious papaya by seed selection and good culture. 
As a result the quality of fruit has been generally improved. Dur- 
ing this time the fruit-bearing plants have considerably exceeded 
the staminate plants in number. The staminate plants constituted 
36 per cent of those that began fruiting in the field in 1924 and 51 
Figure 12. — Pyriform and spherical-shaped fruit of the Solo papaya 
per cent of those growing on a very small area and fruiting for the 
first time in 1927. 
Change of shape of fruit on the plants of an entire field occasion- 
ally takes place. A fair instance of this occurred in an experiment 
at the station during the season of 1923-24. The plants were pro- 
duced from the seed of a long fruit of the monoecious type as 
represented in Figure 3. All the fruits were true in form to the 
parent type during 1923. The following summer, however, the 
same plants bore large spindle-shaped fruit with diameters equal to 
about one-half or more of their respective lengths. It was suspected 
that cross-pollination had influenced these variations direct, but 
results of a cross-pollination experiment in a near-by field at the 
station in the fall of 1924 failed to show that change of shape of 
fruit is caused by the stimulus of cross-pollination. 
Often individual plants may bear fruit only a part of which is 
of unusual form. These variations take place in both the pistillate 
