20, 1 Wells and Perkins: Nipa-sugar Manufacture AT 
of tuba from each stalk also seem to be greater. The number 
of fruits per hectare, however, in the Capiz swamps that ‘were 
visited is much less than that in the Manila Bay swamps. This 
is probably because the Capiz swamps have not been extensively 
used for tuba for a number of years and have been allowed to 
become dense. The quality of the tuba is about the same (15 
per cent sugar) in both places. Just why the Capiz swamps 
have a sturdier growth is not evident. 
The relatively small nipa swamps near Catarman are affected 
by the strong ocean tides, which cut out deep, narrow channels. 
This is unfavorable to nipa, as much of the swamp is too high 
for it and is covered with grass and other dry-land plants (Plate 
2, fig. 1). The channels themselves are too deep for the nipa, 
which is forced to grow on steep banks (Plate 2, figs. 2 and 8). 
In spite of this fact, and of the crowded condition of the swamps, 
fruits were found to be plentiful, but the tuba was found to be 
of poor quality (10 to 12 per cent sucrose). 
Besides these general differences between swamps, the plants 
in a given swamp vary considerably in yield and quality of tuba. 
How much of this is due to environment and how much can be 
controlled by a proper selection of seed is a question for valuable 
but rather tedious experimental work. 
Another interesting and important point is the preparation 
of the fruit stalk for tuba flow: Gibbs says:° “According to 
native superstition the stalk must be kicked, in passing, once 
a week for five weeks, before it is cut or the sap will not flow 
freely.” The experiments of the writers incline them to believe 
this “superstition.” Several unprepared fruits of different ages 
which were cut left only dry stalks which did not give a drop of 
tuba in any case. . 
PRESERVATION OF TUBA 
The very rapid disappearance of crystallizable sugar in tuba 
is undoubtedly due in large part to enzymes or zymogen ° present 
in the sap itself. Without the help of microérganisms, however, 
these enzymes are not very effective. The fresh juice is practic- 
ally neutral to phenolphthalein, sometimes giving a slight color, 
which shows that it is not a favorable medium for the action 
of invertase. Yeast and bacterial life, however, are very 
*Philip. Journ. Sci. § A 6 (1911) 116, but cf. Conrado, A., and Zébel, 
E., Estudio de la planta llamada nipa. Imp. de la Concepcién, Manila 
(1906) 12. 
* Gibbs, op. cit. 124; Pratt, op. cit. 382. 
