Of the yield of the plantain we possess much more accurate information.  A new plantain walk in this colony (British Guiana) will yield 450 bunches, of 50 lbs. each, of which, as nearly as possible, 50 per cent. will be of core, containing 17 per cent. of starch, thus producing 17 cwt. of starch per acre.  But an old plantain walk, even when free from disease, could not be reckoned to yield more than half this quantity, namely, 81/2 cwt. per acre.  Considering the value that is set on the plantain as an article of food, and the difficulties incident to the process of making starch from it, it is by no means probable that it will ever be used as a source from which to obtain starch.

Of the quantity of arrowroot that can be grown per acre, I have been able (continues Dr. Shier) to procure no information; but from the price it commands in the market, the facility with which it can be grown, and the ease with which the process of separating the starch can be carried on, it deserves a fair trial here.  To cultivate it to advantage it ought to be done on thorough-drained and well-tilled land, planted at the proper season, and not dug till ripe and in dry weather.

Of the Tous les mois, I have only been able to procure a single plant, for which I am indebted to the kindness of the Hon. John Croal.  As the root was immature, it would be unfair to deduce from the quantity of starch obtained, the per centage generally contained by the plant.  Its immaturity was also indicated by the globules being smaller than in the specimen obtained from Grenada; in other respects, however, such as the tenacity of its jelly, it stands highest.  It is altogether one of the most promising starch-producing plants, and obviously deserves a careful trial.  It is a plant that expends a good deal of matter in maturing a considerable quantity of dense and bulky seeds, but as it propagates both by root and seed, it is probable that, as a root-crop, it would be highly advantageous to procure a variety that does not flower.

Both the tannia and the sweet potato can be readily grown, and the produce per acre is large; but from the foregoing tables it would appear that there are other plants whose starch is likely to be held in greater estimation.

Difficulties attendant on the process of preparing starch.—­Were the manufacture of superior starch to be carried out in this colony (British Guiana) on a large scale and profitably, recourse would require to be had to all the well-known means of economising labor.  In the cultivation as much as possible would require to be done by cattle and implement labor, and this would be the easier to accomplish, inasmuch as, to grow roots to great advantage, the land would require to be thorough drained.  When the produce was brought to the buildings, machinery similar to what is already in use in Europe, for the purpose of washing and rasping roots, and of separating and washing starch, would suffice with comparatively little