41 
any pollen. All of those flowers, pollinated and unpollinated alike, 
produced fruit but no seed. Those unpollinated furnish another 
clear case of parthenocarpy. In the case of those that were hand- 
pollinated the pollen appears to have been wholly without influence, 
being in this respect unlike those of Nos. 2491, 2493, and 2494, referred 
to above. It is also fair to conclude that seedlessness in this tree was 
not due to a lack of fertile pollen, because pollen was actually applied 
to the stigmas, and also because an abundant supply of effective pollen 
was present in the orchard, as evidenced by the presence of many 
seeds in the fruits of other trees. 
Other instances of parthenocarpy in papaya have been observed. 
Xo. 1996:37, a pistillate tree of a dioecious stock whose male trees 
showed some tendency to bear hermaphrodite flowers, exhibited this 
phenomenon. Several of its flowers which were sealed in paraffined 
sacks to prevent pollination grew into normal fruits and after three 
months were cut open and found to be seedless. On the same tree 
other fruits from flowers which had not been sealed were found to 
contain many seeds. It is apparent that the carpels of these flowers 
were capable of development with or without the influence of pollen. 
In the above it will be observed that the fourteenth and fifteenth 
pollinations proved successful in only a few cases. It is to be noted 
that the mother trees in all these instances were of the No. 2474 stock? 
which was the progeny of the No. 1996 stock which exhibited the 
tendency to parthenocarpy, although it did not refuse pollination. 
This suggests the tr admissibility of parthenocarpic tendencies. 
It is apparent, therefore, that parthenocarpy is not rare in the 
papaya, but that it is not the rule is proved by a large number of 
observations and experiments. Pistillate flowers of most papaya 
trees will fail to set fruit if prevented from receiving pollen. 
PARTHENOGENE SIS. 
Cases of parthenogenesis have been watched for but none has been 
recorded. In one instance where no pollen came in contact with the 
stigma the fruit was found to contain one seed, but this proved to be 
infertile. 
HYBRIDIZATION OF CARICA. 
Ic is probable that there has been considerable hybridizing of 
Carica by natural means and the genus has not been wholly neglected 
by plant breeders. 1 C. cundinamarcensis has been crossed with the 
pollen of C. papaya. Also C. cauliflora as a mother plant has been 
crossed with C. papaya. Van Volxem 2 crossed C. erythrocarpa with 
the pollen of C. cundinamarcensis and then proceeded to inbreed by 
crossing his new hybrid as a mother plant with C. cundinamarcensis. 
I cf. Solms-Laubach and also Andre in articles referred to above. 
* J. van Volxem. Gard. Chron., n. ser., 14 (1880), p. 729. 
