74. Canna edulis, Ker.—Tous-les-Mois?

Sex. Syst. Monandria, Monogynia.
(Canna. Fecula of the root of an imperfectly determined species of Canna. Tous-les-Mois, E.—The root is supposed to furnish the fecula called Tous-les-Moit, D.)

The starch or fecula called Tous les-Mois was introduced to the notice of the British public by the late Mr. Olpherts [Hamilton, Pharm. Journal, vol. vii. p. 56, 1847; also, the Medico-Chirurg. Review for Oct. 1, 1836; and Ryan's Med. and Surg. Journal for August, 1836.] of St. Kitts, about 1836. It was at first stated to be the produce of C. coccinea; but as this species, like C. indica, has fibrous, and not tuberous roots, it is tolerably clear that this cannot be the source of the starch in question.

There is good reason for believing that C. edulis of Ker is a native of the West Indies, and that it is the species which yields tous les-mois. Descourtilz [Fl. Méd. des Antilles, p. 3, tab. 240.] and Lunan [Hortus Jamaicensis, vol. ii. p. 417.] speak of a species of Canna with fleshy tuberous roots, which grows in the West Indies, and which they call C. indica. But the character of the roots just mentioned shows that the West Indian plant is not C. indica, Linn. Ruiz and Pavon [Flora Peruviana.] speak of a South American plant which they term Canna indica of Linnaeus, whose fleshy tubers are eaten by the Peruvians, who call the plant Achira. They considered it to be the C. Indica of Linn. But when their herbarium came into Mr. Lambert's possession, he raised plants from the seeds of the original specimens, and found the species to be a new one, which he named C. edulis. [Botanical Register, tab. 7.]

Mr. Lambert afterwards received seeds, from Dr. Gillies of Mendoza, of a Canna known in South America as "Achira." This has been described and figured [Ibid. tab. 1358.] as a new species under the name of C. Achiras (more properly C. Achira); but it is not improbable that it may prove to be identical with C. edulis.

C. glauca is also said to yield a valuable starch. [Bennett, Ceylon and its Capabilities, p. 127, 1843.]

Fig. 224. Wheel-rasp My friend Mr. Wordsworth, assistant-surgeon to the London Hospital, and who resided some time at St. Kitts, tells me that he cultivated the Tous-les-Mois in his garden. Its height was about 4 feet; and its tubers three or four times the size of the fist. In order to extract the fecula, the tubers are rasped by means of a circular or wheel-rasp [Piso (Hist. Nat. Brasiliae, p. 53, 1648) represents a somewhat similar machine as being used in the preparation of cassava or tapioca starch.] worked by a treddle. The tuber is held against the edge of the rasp, at the point marked a in the accompanying figure. The starch is obtained from this pulp by the ordinary methods of washing, straining, decantation of the supernatant liquor, and desiccation of the deposited starch.

The quantity of starch procured from the roots of the tous-les-mois plant has not been satisfactorily ascertained. Ricord Madianna [Journ. de Pharmacie, t. xvi. p. 306, 1830.] obtained from a pound of the root two ounces of a starch of fine quality: this is equal to 12.5 per cent. It is probable, however, that on the large scale the product would be much greater.

Tous-les-mois starch is imported from St. Kitts. To the naked eye it greatly resembles potato-starch. On account of the large size of its particles, it has a satiny or glistening appearance, and is devoid of that dead white or opake appearance presented by the West Indian arrowroot. Examined by a pocket lens, the sparkling and glistening appearance of its particles is very obvious. When submitted to examination by means of the compound microscope, its particles are seen to be very large [The following measurements, in parts of an English inch, of the particles of "tous-les-mois," were made for me by Mr. George Jackson:—Particles. Length. Breadth. 1. 0.0042 0.0035 2. 0.0037. 0.0026. 3*. 0.0031. 0.0027. 4*. 0.0032 0.0020 5*. 0.0025 0.0017. 6. 0.0013 0.0010. The most prevalent-sized particles are those marked thus *.

] (in this respect exceeding those of all other starches), somewhat egg-shaped, to have a very distinct nucleus, central cavity, or hilum, and concentric rings indicative of their laminated structure. Strictly speaking, their shape is oval or oblong; but generally more or less ovate. The circular hilum is usually placed at the narrow extremity; very rarely it is double; once I have seen it treble. The rings are numerous, regular, close, but somewhat unequally so. The hilum and the body of the particle are frequently cracked.

Potato-starch is the only amylaceous substance which can be confounded with tous-les-mois. The two starches maybe distinguished by a careful attention to their relative sizes and shapes, to the appearance of their rings, the position of the hilum, and the action of polarized light on them.

First, the particles of potato-starch are on the average smaller than those of tous-les-mois, and are subject to greater irregularity of size (both as regards different sorts of potatoes and the different particles of the same potato).

Secondly, the larger particles of potato-starch are more irregular in shape than those of tous-les-mois; the latter are more constantly rounded or oblong or ovate-oblong; the former are oval, often approximating in shape to an oyster-shell, a mussel-shell, or a triangle with rounded corners, and being frequently gibbous or tumid at different parts of their surface.

Thirdly, the rings seen on particles of tous-les-mois are fine, regular, uniform, concentric, and crowded; those of potato-starch are coarser, irregular, often excentric, irregularly drawn out, distorted, or more and unequally distant from each other. In potato-starch a greater number of complete rings is visible, and we can trace the lines around the hilum, even in the case of many of the larger rings; but in tous-les-mois this can be done with a very few of the smaller rings only.

Fourthly, in both the hilum is situated nearer to the end of the particle; but in potato-starch this character is less obvious, the hilum frequently being less distant from the centre of the particle than in the case of tous-les-mois.

Lastly, when viewed by polarized light the cross is less frequently regular in potato-starch than in tous-les-mois; in the former, the arms are often distorted.

Tons-les-mois of commerce contains about 16.74 per cent. of hygroscopic water. It is very soluble in boiling water; and, according to Dr. Shier's experiments, yields a jelly, which is considerably more tenacious than the jelly of any other starch; but which, in clearness or translucency, is inferior to that of arrow-root, and of some other substances.

The composition of tous-les-mois starch is assumed to be the same as that of other starches, viz., C12H10O10.

In its dietetical qualities tous-les-mois resembles other starches (see vol. i. p. 116). It yields very agreeable articles of food for invalids and others, and appears to be very readily digested.
