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of very numerous bundles of needle-shaped crystals, and we also found similar crystals in the leaves and stems. These crystals were seen under the microscope to be insoluble in cold acetic acid, but easily soluble in cold diluted nitric or hydrochloric acid." " There appears to us to be no reason to doubt the fact, that the whole of the physiological symptoms caused by Arums are due to these needle-shaped crystals of oxalate of lime, and that the symptoms are thus due to purely mechanical causes. Bearing in mind the action of re-agents on calcic oxalate, the reason why mere boiling in water failed to deprive them of their activity is explained by the insolubility of oxalate of lime in water. Again, the action of dilute acetic acid, even at temperatures of 100° C, in slightly lessening the activity of the tubers, is due to the very slight solubility of oxalate of lime in that acid And, lastly, the complete loss of all physiological action when the tubers were treated with dilute nitric or hydrochloric acid is evidently due to the ready solubility of calcic oxalate in those mineral acids. And these assumptions, as we have already indicated, were fully demonstrated by the microscopic examination of sections of the tubers treated with the reagents we have mentioned. One point, however, remains to be explained : we observed that, on drying, the tubers lost practically the whole of their physiological activity. Clearly there could have been no loss of oxalate of lime on desiccation, and, as a matter of fact, we found as many crystals on microscopic examination of dried Arums as we had found in the fresh tubers. We explain this apparent anomaly in the following simple manner. In the fresh condition of the tubers, the bundles of crystals of oxalate of lime are cone-shaped, more or less, the sharp points covering a wide area, and forming the base, but, in the drying of the tubers, the needles appear to arrange themselves more or less parallel to one another, and the sharp points thus cover a smaller area. And thus, instead of each crystal acting as a separate source of irritation and penetrating the tissues, the bundles act as a whole." (Warden and Pedler).

Syn. : — Arum indicum, Roxb. 625.

Sans. : — Mânaka.

Vern. :— Mânakanda (H.); Mânkochu (B. and Ass.) ; Alû (Mar.).

Habitat :— Generally cultivated around the huts of the poorer classes in Bengal.

Tuberous tall coarse herb. Stems attaining 8ft. stout, 3-8in. diam., emitting bulbiferous suckers. Leaves 2-3ft. large, ovate deeply and sagittately cordate repand, lobes rounded very shortly connate, sinus narrow, nerves about 8 pair, petiole stout, transversely clouded. Peduncles (always in pairs, Roxb.) shorter than the petioles. Spathe 8-12in., pale-yellow, green ; tube