23 
*"I'here was an undoubted loss of crop on the two branches that 
were not fertilized at all, 2.¢., berries that never swelled at all. 
Yours faithfully, 
N. G. B. Kirwan.” 
14, So far as it concerns the actual pollination of the coffee plant, 
the foregoing experiments appear to show (1) that the aid of insects is 
not essential but that fertilization can and does take place when all 
insects are excluded during the whole period that the flower is out, 
and (2) that wind, and similar natural agencies, are also not essential 
factors, since the muslin bags used in experiment I-A were of 
sufficiently fine material to exclude pollen altogether. These results 
were certainly very unexpected, but some light on the subject seems to 
be afforded by Dr. von Faber’s experiments of which I only became 
aware after mine had been done, when Dr. Coleman published the 
following note in the “ Planters’ Chronicle” (Volume VIII, pages 
350—351; 19th July 1913) :— 
“In 1910, my friend Dr. F.C. von Faber published in Dutch 
some notes on the biology of the coffee flower in which he gives the 
results of experiments performed by him on fertilization. He experi- 
mented with Liberia coffee and under Javanese conditions so that 
these results cannot be taken directly as applying to South India. 
They however suggest a line of investigation which might, perhaps, 
be profitably followed here in studying the question of the importance 
of cross-fertilization. 
“ Dr. von Faber first examined the question of pollination and 
found tbat out of 78 flowers of Liberia coffee examined, in all but eight 
self-pollination had occurred in the bud before the flowers opened ; 
moreover the pollen grains had in many cases, already germinated at 
the time of opening of the flower and the pollen tubes had begun to 
grow down through tissues of the style towards the ovaries. 
* From this result one might be tempted to conclude that, in the 
case of Liberia coffee, cross-fertilization can occur in so few cases as to. 
be quite negligible. This is, however, not the case, as, on further 
investigation, Dr. von Faber found that, where pollen from other 
flowers on the same plant or from uther plants found its way to the 
stigma and germinated, it grew about twice as fast as the pollen from 
the same flower. There thus occurs a sort of race between the foreign 
and the “self” pollen tubes as to which shall fertilize the ovaries and 
the results depend entirely upon how early the foreign pollen reaches 
the stigma. 
“Dr. von Faber has also some remarks to make on the réle of 
insects in the fertilization of Liberia coffee flowers. He states that, 
although the number of insects in a coffee plantation is usually small 
in comparison with the number of trees, this is to a certain extent 
equalized by the rapidity of insect movement, whereby a large number 
of flowers are visited in a very short time. Bees seem to have been 
among the most prominent insects observed by him. The following 
observations made by him are of interest :— 
6th April—Tree No. 8—At 8 a.m., 48 flowers found open; 
within 15 minutes, 32 of these were visited by insects. 
25th April.—Tree No. 7-a—At8 a.m. 72 flowers found open; 
within 25 minutes, 48 of these were visited by insects. 
