1344 INDIAN MEDICINAL PLANTS. 



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 assumptious, 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). 



1318. Alocasia Indica, Schott, h.f.b.i., vi. 525. 



Syn. : — Arum indicum, Roxb. 625. 



Sans. : — Manaka. 



Vern. :— Manakanda (H.); Mankochu (B. and Ass.) ; Alu 

 (Mar.). 



Habitat :— Generally cultivated around the huts of the poor- 

 er 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 



