I shall extract largely from a very valuable report drawn up by Dr. John Shier, agricultural chemist, of Demerara, and submitted to the Governor of that colony in 1847, on the starch-producing plants, which is deserving of more widely extended publicity than the merely local circulation it has received.  The remarks and results of experiments are worthy of deep consideration; and although they were meant to apply specially to British Guiana, they are equally pertinent to the West India colonies generally, our African and Australian settlements, and many other of our foreign possessions.

For many reasons it is desirable that the number of the staples of cultivation and export of our colonies should be increased.  It is the general experience of British agriculturists, that the mixed system of agriculture is more profitable to the farmer and safer for the land, than the continued cultivation of any single crop, or indeed of nearly allied crops; and although fewer valid objections can be urged against the continued cultivation of the sugar cane, when properly conducted, than against that of grain crops, it is nevertheless certain that a well-arranged alternation or rotation of crops would be better.  When an efficient system of covered drainage is adopted in British Guiana, there can be no doubt that the sugar cane will be replanted at shorter intervals of time than at present, and that other crops, such as provender crops for cattle, and provision crops for the colonial and perhaps the home market, will be made to alternate in cultivation with the cane.  When the cane rows are as far apart as they require to be, to admit of sufficient tillage with the plough and other implements, it will also be possible to intercalate crops of rapidly growing plants; and were this done, as it easily might, in such a manner as to prevent undue exhaustion of the land, or impoverishment of the sugar crop, the returns could not fail to be materially increased.  It would then probably be found that the fluctuations in prices would be less felt, for they would not likely, at the same time, affect different crops in the same manner.

It has been ascertained, in regard to some plants at least, that a much larger return can be obtained in the colonies than can be grown in temperate countries, however fertile.  This is partly owing to the greater fertility of the soil under powerful tropical atmospheric influences, and partly to the fact that vegetation is continuous throughout the year, so that slow growing plants can do more within the time, from their functions not being arrested by the chill of winter; and of many rapidly growing plants, two successive crops can be grown within the year.

Starch is a substance easily manufactured, and being largely used in several of the arts, as well as an article of diet, there consequently exists a considerable demand for it in England.  It may be obtained from a great variety of plants, and many of the most productive of it are natives of the tropics.