SOME ILLUSTRATIONS OF PODS 21 



largest numbers where trees were exposed to sunlight, or 

 where flowers were thus exposed by the pollarding of the 

 branches of the cacao-trees. Isolated cacao-trees do bear 

 large crops, but this may be due to the increased or un- 

 limited food-supply available to such specimens, as well as 

 to the increase in the number of pollinating insects." 



In Trinidad generally there are at present few or no 

 " thrips " on cacao, so that pollination cannot be de- 

 pendent on that class of insect alone, or there would be no 

 cacao. If the "mortel " shade were to be removed as has 

 been proposed, " thrips " would probably increase. Wright 

 also mentions that Green (entomologist) has recorded in 

 Ceylon the occurrence of thirty specimens of a common 

 aphis (Ceylonia theceecola, Buckt) in a cacao flower, each 

 being dusted with numerous pollen grains. The flower 

 itself is so formed that it appears almost impossible for 

 pollination to be effected without some extraneous aid, and 

 to the present time the evidence appears strongly in favour 

 of the view that pollination is accomplished by the aid of 

 minute insects, thrips, aphis, &c., and so far as it goes con- 

 firms the correctness of our incomplete investigation. To 

 ascertain correctly the means by which cacao is in general 

 fertilised would require the undivided study of a biologist 

 for a very lengthy period. In the West Indies little trouble 

 is felt at any want of effective pollination as fertilisation is 

 regularly effected in proportion to the flowers that appear, 

 unless abnormal weather occurs, in extremes of drought 

 or rainfall ; either of which will cause a dropping of the 

 pod, even after full pollination has been effected. 



