120 
In the ease of the former, the value of the results seems 
dependent on the uniformity of the yields of the two control plots 
and their agreement with the yield of the plots now treated in the 
years prior to their ti'eatment, while in the case of the latter the use 
of the control is quite subordinated, one only being used, and no 
indication of the range of variation or the causes of variations in the 
plots under uniform tr3atment is obtainable. 
As far as published results go, and certainly as far as theoretical 
considerations direct experiment, the only rational way where 
experiment is framed on yield estimation (there are numerous cases 
where growth-record experiments may be used to advantage) seems 
to be the utilization of the results of an initial investigation of yield- 
differences over a large number of blocks of palms similarly treated, 
and the value of controls as a check certainly seem to lie in the 
detection of the range between their maximum and minimum values. 
It is difficult in a paper of this nature and length, to indicate 
clearly the interpretation which the experimenter will put to his 
records, but the citation of the points above mentioned may not be 
without interest in the light of what follows. 
Taken together they lie at the basis of the problem which every 
estate manager is confronted with, viz., estimates — the one concern- 
ing which he thanks his good fortune if his figures of crops for any 
period in advance approaches the figures of the actual crops 
produced. 
It has been mentioned previously in this paper, that experiments 
are in hand to investigate the question of the incremental-crop produced 
in young palms. Whatever values may be ultimately determined 
by experimentation as being theoretically possible, there is the ever 
present fact that the arrears in the number of ripe nuts obtained 
under present conditions and methods are disproportionately great, 
and here we approach the question of “ falling nuts.” So far, the 
actual numbers have not been obtained for mature palms but it 
is extremely probable that they are of high magnitude. In general 
the nuts which fall may be placed into the following categories : 
(a) Those which are unpollinated and therefore unfertilized ; 
(b) Those which are pollinated but in which fertilization 
does not eventuate ; 
(c) Those which are pollinated and fertilized but which are 
thrown off in the run of the physiology of the tree 
for reasons of the trees’ inability to carry them. 
Nutritional factors — water supply in particular — will 
here play an important part, and may possibly largely 
determine periodicity in crop production. 
In young palms category (e) will probably account for a larger 
number than has been previously supposed and similarly in the case 
