602 



in a fresh state [see Leather, '' Cyanogeneses in Plants/' Agric! 

 Journ. India, i. 1906, pt. 3, pp. 223-224; Dimstan, Henry & 

 Auld, " Phaseolunatin in Cassava," Proc. Roy. Soc. Ixxviii. 

 1906, pp. 152-158], and under cultivation there are numerous 

 varieties of both forms often confined to certain locahties. In 



Avians or easily 



India 



boilable kinds" and " Mara vans or dark races," varying in 

 height from 3-25 ft. ; age at maturity 6-15 months and average 

 weight of roots 4-25 lb. (Sawyer, Indian Forester, 1895, p. 290 : 

 Burkill, Agric. Ledger No. 10, 1904, p. 125), the jield per acre 



The West Indies, 



^ from 



Colombia, Brazil, &c., all have many varieties, native or intro- 

 duced and it would be quite impossible to detail them here {see 

 refs. at end) ; they include such names as '' Bunch of Keys,'* 

 " Yellow Belly/' '' Blue " " Black-" '' White-" '' Brown-'^ 

 "Butter-" "Sweet" and "Silver" Sticks; "Red Jacket," 

 " Red " and " White Greenaway," &c. 



In Nigeria and Dahomey three principal • varieties are 

 distinguished — -" Black Manioc," with a dark-coloured stalk, 

 a root with a black cortex and numerous roots, 10 to 15 in good 

 soil, attaining a length of 24-28 in.— " White Manioc," Hght- 

 grey stalk, few roots, 3 or 4 of large size, sometimes 39 in. in 

 length, and half-a-dozen smaller ones, — and "Red Manioc" 

 with red-brown stalk, roots with a reddish-brown cortex, 

 numerous, but of smaller size than in the two foregoing. The 

 black is said to yield the best flour and the white is grown 

 especially for making flour. The period of growth varies according 

 to the purpose for which the plants are required ; the red and 

 black are the earliest, the roots being dug up at 5, 7 or 8 months 

 if they are to be eaten cooked and after 2 or 3 years if they are 

 to be made into flour, the w^hite as indicated above being usually 

 grown as it yields the heaviest crops — this having been found 

 in Dahomey to be from 16,800-32,100 kg. per ha. (134-256 cwt. 

 per acre) (Henry & Ammann, " Les Manioc Africain " seq.). 

 These authors also state that the tliree principal varieties grow n 

 in Dahomey on other than forest land give a product which 

 can be eaten \vithout further treatment, but the roots of tw^o 

 of the same varieties — red and w^hite, cultivated on forest soil 



much 



serious accidents. 



■equirements are rich, light w^ell- drained 



a hot chmate at all seasons and a moderate rainfall. Plants 

 may be raised from seed but cuttings 6 in, or more long are 

 recommended, nlanted in rows 4 ft. anart or thereabouts in the 



put in at the 



time 



field, or they may be rooted in nurser 



beginning of the rainy season or at any 



degree of moisture can be assured. In the United States it is 



recommended to put in cuttings 4^6 in. in length in ploughed 



furrows, Uke planting potatoes, and covering with 2-4 in. of 



soil (Tracy, U. S, Dept. Agric. Farmers' Bull. No. 167, 1903, 



