RANGE AND CLIMATE 



25 



The temperature range has a very important bearing on the composition 

 of the cane. In those places that have a uniformly high temperature 

 and no cool season, an impure cane of low sugar content and high in reducing 

 sugars is almost invariably harvested. In such a case there is opportunity 

 for continuous vegetative growth, and the crop as it reaches the mill will 

 consist of canes in full vegetative vigour, of ripe, and of over-ripe canes. 

 The non-sugars present will consist of products in process of metabolic 

 change, and of degradation products formed from the breaking down of 

 the cane sugar. In extra-tropical climates, such as in Louisiana, the 

 limited period of growth affords a cane that does not have an opportunity 

 to reach maturity. A j nice low in solids, sugar and purity, and high in reduc- 

 ing sugars, results, the latter bodies representing material in course of trans- 

 formation to cane sugar. A sweet and pure cane is found in those regions 

 where a longer period is taken to maturity, combined with a season sufficiently 

 cold to check the vegetative vigour of the plant, whereby its energy is directed 

 towards the elaboration into cane sugar of material already in the process 

 of transformation. Those localities lying on the confines of the tropics 

 present these conditions, and when, as in the arid districts of the Hawaiian 

 Islands and of Peru, water can be withheld from the plant and that in the 

 plant can be transpired, the sweetest and purest material results. 



The writer is aware of only one attempt to correlate temperature and 

 composition, and this was made by Michaud^^ in Costa Rica. With due 

 regard to the elimination of experimental and of personal error, he caused 

 ripe canes of the Red Ribbon variety to be collected at various altitudes, 

 the temperatures of which were known or could be interpolated. The latitude 

 of Costa Rica is 8°-ii° N., its coast line lying on the heat equator, and though 

 the influence of rainfall is not included, the results tabulated below, with 

 one exception obviously abnormal, agree with the remarks made immediately 

 above, regarding the effect of temperature as controlled by latitude. 



Effect of Temperature on the Composition of the Cane (Michaud). 



Temper- Sugar Water Sugar Solids 



Altitude ature per cent. per cent. per cent. per cent. Purity 



feet F° cane cane juice juice 



5,937 62-5 i5'6o 72-43 i8'76 22-o8 84-99 



5.379 64-5 15-59 73-24 18-71 2o-8o 89-98 



4,547 66-0 16-38 71-96 19-84 22-21 89-36 



4,195 68-0 16-45 71*34 20-11 21-21 94*83 



3,641 70-0 16-63 71-29 20-32 22-IO 91*95 



2,844 T^' 5 17-00 71*34 20-42 24-60 82-99 



2,361 74*5 17*38 73*94 20-50 21-98 93*29 



1,148 78-0 16-80 74-00 19-88 20-98 94*77 



718 79*0 16-06 74-60 18-92 20-86 90-68 



33 8o-5 14-45 75*38 17*08 18-60 91*85 



The effect of rainfall on the crop is more than a matter of the total fall, 

 its distribution being of equal importance. It is at once patent that a fall 

 of 10 inches in 24 hours is less beneficial than five precipitations of 2 inches 

 separated by weekly intervals. Walter^^ in discussing this subject intro- 

 duces the terms " inefficient rainfall " and " degree of wetness." The latter 

 he defines as Rf^/t where R is the rainfall, t is the days in a month and t^ 

 is the number of rain^^ days in that month. The Mauritius statistics as 

 collated by him for the period 1892-1905 are given below, as the}^ serve to 

 demonstrate the combined effect of rain and temperature on the crop 

 harvested. 



