CROP-PLANTS 361 



In Nigeria during the last few years experiments have been 

 made in producing tapioca from cassava by a simple process of 

 grating and washing. An investigation as to the possibilty of 

 establishing an export trade in tapioca was carried out by the 

 department of agriculture in 1935, and it was decided that it 

 would be more profitable to concentrate on the production of 

 starch flour. (Nigeria, Agriculture, 1935, D.R.) 



The manufacture of tapioca has been introduced in other ter- 

 ritories also: for example, in French Togoland a factory has been 

 established and an export developed. Each native farmer and his 

 family perform every process for themselves, growing the crop, 

 grinding the roots, washing the pulp through a series of tanks to 

 float off the cellulose, cooking the pure starch and finally packing 

 the finished product. It is claimed that an industry thus based on 

 the family unit can be developed as an integral part of the ordinary 

 tribal life. The adoption of these processes has been encouraged 

 with a view to the development of exports; their application to the 

 preparation of food for native consumption would probably in- 

 crease the nutritive value of the plant, particularly in the case of 

 the bitter cassava, in which the cyanogentic glucosides, which have 

 been shown to produce pellagra, are more pronounced. 



Sweet potatoes [Ipomaea batatas), which are widely grown for local 

 food, exist in very numerous varieties. Variety trials, to test yields 

 and quality, have been carried out in several territories. Trials 

 at the Ngetta substation of the agricultural department, Tangan- 

 yika, showed that the best yielders were not nearly so acceptable 

 to the native farmer as lower-yielding varieties, which have a 

 better flavour. The trial of West African varieties has been carried 

 out at the Samaru station in Northern Nigeria. 



The vine of the sweet potato is valuable for forage and is also 

 used as spinach by natives of West Africa. At the Shika Govern- 

 ment stock farm near Zaria in Northern Nigeria sweet potatoes 

 are in fact grown as the principal fodder crop. The vines last 

 throughout the dry season, and they can be cut twice per annum 

 at the expense of some development of the tubers. The tubers 

 themselves form a valuable cattle food, but of course they are still 

 more useful for feeding human beings. In parts of East Africa, 

 notably the Kikuyu country, the sweet potato has been replaced 



