41 



The following table suggests, but does not ])rove that they 

 were i)laced at a disadvantage. 



being a reduction u]jon the longest of 

 the shorter 

 the short 



4G ])er cent. 

 40 „ 

 32 



The figures also suggest that it is not the longeijt and deepest 

 going which give the largest returns; but that those whicli are half- 

 long, or ])er]ia|)s one might say betwt'eii half-long and long, are the 

 most ])rolific. 



The return ])er area, but not the relative return was interfered 

 Avith by thieves who robbed at night but not discriminatingly, taking 

 from the back of the bed where they thought their ojicrations most 

 hidden. 



In this Bulletin, \\)1. T, p. 3()(j the advantage to the new plant 

 of using the to]) of tlie old tuber for a set was stated, and on ]). 307. 

 it was sliown by how much these tops give an early start to tlie new 

 shoot. In 1917 toj) halves v\Tre idanted against bottom halves in 

 no less than 56 races, 154 tops against 136 bottoms. In 42 races 

 the average weight of the tubers produced by the tops was greater 

 than the average weight of tuber produced from the bottoms, and 

 in 13 cases it was the reverse. 



Most of the races grown have now been tried cooked at least 

 once; l)ut so long ^as the Cardens are without the use ol' a lal)oratory, 

 accurate comparisons are most difficult to make. The oijinion has 

 been formed that all the upgrowing yams are excellent for tlie table 

 when pro])erly cooked. Ihe others vary a little among themselves. 

 Further examinations will he made, especially with a vi(nv to desist- 

 ing from cultivating that which is inferior. 



Hitherto tbe study of the morphology of the tubers has de- 

 manded tbe cultivation of them all. 



The classification resulting may be ex])ressed l^y the following 

 table wherein the numbers given denote the races which have been 

 figured. 



