620 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
stigma. But in spite of their agreement in this feature of holding 
the stamens away from the pistil, the floral biology of the two trees 
is apparently very different. 
The caulocarpous habit, shared by cacao with many tropical trees, 
has been looked upon as an adaptation to favor cross-fertilization 
by ants or other small crawling insects, but the striking form and 
conspicuous coloration of the cacao flowers, as well as their highly 
specialized structure, suggests that flying insects are attracted. 
The glandular pubescence of the calyx and sepals may also be con- 
sidered as an adaptation that tends to discourage the attention of 
small crawling insects. 
With the patashte the case is obviously different. The petals, 
instead of being conspicuous and bright-colored, are greatly reduced, 
or even rudimentary. The dull color of the flowers and their alto- 
gether different position on the tree make it evident that they are 
not adapted to attract the same class of insect visitors as the flowers 
of the cacao. The patashte flowers are carried up to the light and 
are probably visited by bees or other sun-loving, day-flying insects 
that might never go down into the darkness to find the flowers of 
cacao. The nonglandular character of the pubescence of the patashte 
flowers may be significant from this point of view. 
A new interpretation of the floral biology of cacao is presented in 
a recent work by Dr.C.J.J.van Hall. The fact of variation among 
cacao seedlings is brought forward as evidence that crossing is of 
frequent occurrence, and the following explanation is given: 
This strong intercrossing indicates that the pollen can be transported from one tree 
to another. The transport might be effected in two ways, either by wind, or by 
flying insects such as butterflies, wasps, bees, flies—but not by thrips, aphides, or 
ants, none of which fly at all, and of which thrips and aphis can only move very 
slowly. 
The question whether pollination takes place by wind or by flying insects seemed at 
first difficult to answer, because the flower of the cocoa does not appear to be adapted 
to wind-pollinisation, and flying insects were never found. Accordingly, the whole 
question for long remained a puzzle. Happily, however, a thorough investigation 
has lately been carried out by Dr. von Faber at Buitenzorg (Java), and this investiga- 
tion solved the question. 
Dr. von Faber has kindly given the present writer a short summary of his results, 
with permission to incorporate it here. He writes as follows: 
“Though the structure of the flower seems to eliminate the possibility of self- 
pollination, this is really not so. The long and supple flower stalk facilitates the swing- 
ing to and fro of the hanging flower by the wind. Experiments proved that by this 
movement pollen easily falls from the anthers on the pistil of the same flower, and it 
could be demonstrated that isolated flowers were easily self-pollinated in this way. 
Self-pollination may therefore be regarded to be the rule in the cocoa-flower. When, 
however, neighbouring trees stand close to each other, it is also possible that the pollen 
falls from the hanging blossoms and settles on the pistil of flowers of the neighbouring 
tree. In this way cross-fertilisation is possible when the trees stand in close proximity, 
as is the case in all plantations.’’ ! 
‘Van Hall, C. J. J. Cocoa 54. (London, 1914.) 
