Within the last three or four years, considerable quantities of a feculent substance, called Tous les mois, have been imported from the West Indies.  It is cultivated in Barbados, St. Kitts, and the French islands, and is said to be prepared by a tedious and troublesome process from the rhizomes of various species of Canna Coccinea, Achiras, glauca, and edulis.  It approaches more nearly to potato starch than to any other fecula, but its particles are larger.  Like the other amylaceous substances, it forms a valuable and nutritious article of food for the invalid.

The large tuberous roots of the Canna are equal in size to the human head.  The plant attains in rich soils a stature of fourteen feet, and is identical, it is supposed, with the Achira of Choco, which has an esculent root highly esteemed; and my friend, Dr. Hamilton, of Plymouth, has named it provisionally, in consequence, Canna achira.  The starch of this root, he asserts, is superior to that of the Maranta.

ROOT CROPS.

Amongst tuberous rooted plants, which serve as food for man in various quarters of the globe, the principal are the common potato, yam, cocoes or eddoes, sweet potatoes, taro, tacca, arrowroot, cassava, or manioc, and the Apios (Arracacha esculenta).  There are others of less importance, which may be incidentally mentioned.  The roots of Tropaeolum tuberosum are eaten in Peru, those of Ocymum tuberosum in Java.  In Kamschatka they use the root of the Lilium Pomponium as a substitute for the potato.  In Brazil the Helianthus tuberosus.  The rhizomae and seed vessels of the Lotus form the principal food of the aborigines of Australia.  As a matter of curious information, I have also briefly alluded to many other plants and roots, furnishing farinaceous substance and support in different countries.

The comparative amount of human food that can be produced upon an acre from different crops, is worthy of great consideration.  One hundred bushels of Indian corn per acre is not an uncommon crop.  One peck per week will not only sustain life, but give a man strength to labor, if the stomach is properly toned to the amount of food.  This, then, would feed one man 400 weeks, or almost eight years! 400 bushels of potatoes can also be raised upon an acre.  This would give a bushel a week for the same length of time; and the actual weight of an acre of sweet potatoes (Convolvulus batatas) is 21,344 lbs., which is not considered an extraordinary crop.  This would feed a man (six pounds a day) for 3,557 days, or nine and two-third years!

To vary the diet we will occasionally give rice, which has been grown at the rate of 93 bushels to the acre, over an entire field.  This, at 45 lbs. to the bushel, would be 4,185 lbs.; or, at 28 lbs. to the bushel when husked, 2,604 lbs., which, at two pounds a day, would feed a man 1,302 days, or more than three-and-a-half years!