It was also shown that the Belladonna root of commerce varies greatly in alkaloid strength. “In a number of analyses made of commercial roots, variations from 0·27 to 0·69 per cent. have occurred. The average of twenty-one analyses of German and Austrian commercial roots was 0·40 per cent. Other observers have recorded similar results. Chevalier (_Compt. Rend._, 1910, 150, 344) gives the following figures for Continental roots: French, 0·300 to 0·450 per cent.; Austrian, 0·251 to 0·372 per cent.; Italian, 0·107 to 0·187 per cent. Henderson has shown the average of thirty samples of foreign root to be 0·3 per cent. It is interesting to observe that the average of nine samples of root grown at Darenth is 0·54 per cent. In order to determine whether this variation was due to collecting at different times of the year, roots from the same plot, derived from second year’s plants, which were sown at the same time, were dug up at intervals and dried. The following is a record of the analysis of these samples:— March, 1911 0·56 per cent. May, 1911 0·59 „ „ June, 1911 0·53 „ „ August, 1911 0·50 „ „ December, 1911 0·59 „ „ “The amount of variation throughout the year is thus seen to be very small.” Dunstan (_Bul. Imp. Inst., 1905_) has shown that _Hyoscyamus muticus_ grown in India yielded 0·3 to 0·4 per cent. of hyoscyamine, but that the same species grown in Egypt produced 0·6 to 1·2 per cent. According to Esser no coniine is found in _Conium maculatum_ growing in the far north. The same authority says that the root of _Hyoscyamus niger_ is quite free from toxic properties in winter. =Variation in the Poisonous Parts of Plants.= As will be shown in succeeding chapters, many plants (_e.g._ meadow saffron) are poisonous in all their parts, though the amount of the toxic substance may differ according as to whether the seeds, leaves, stem or roots are severally considered. In other cases one part of the plant alone is toxic (_e.g._ the seeds, as in corn cockle). Further, some species vary in the percentage of the toxic substance in the leaves before and after flowering. Frequently the root is the most toxic portion of the plant. This point may be usefully recollected in relation to poisoning of live stock, which are in general affected by the foliage or ripe seeds.