STARCH IN THE LEGUMIXOS^ 249 



The shape of the grain is a valuable index to the identifi- 

 cation of starches. It varies considerably from one plant 

 to another, but often retains the same appearance in similar 

 portions of a given variety; whilst it may vary in the root 

 and in the seed of the same plant, if that particular plant 

 contains starch, e.g., Psophocarpus tctragonolobus. 



The hilum may be punctiform, that is, forming a small 

 circular or elliptical surface, stellate, linear, or branched. 



The position of the hilum is sometimes central, some- 

 times eccentric. The side on which it is situated should be 

 given, either on the small or on the large side. 



The striations are for the most part scarcely visible, and 

 are only distinguished through their more or less crowded 

 arrangement and their more or less accentuated curvature. 

 The hilum acts as a centre to the striations, which approach 

 the circular in shape, and the intervals between them vary 

 according to the position of the nucleus. 



These few details on the method of formation of starch 

 grains and their distinctive characters have been given in 

 order to enable the reader to understand better the examina- 

 tions which have been made of different peas and other 

 Leguminos£e. Thev mav thus prove useful to any who wish 

 to extend existing researches. 



CHARACTERS OF THE PRINCIPAL STARCHES IN THE LECUMINOS^. 



Arachis hypogaea (Pea-nut). — Seeds very poor in starch. The shape 

 of the grains is very uniform, usually round, some are double the size 

 of others. Polarization is only observed in the large grains. The 

 hilum, chiefly visible in the big grains, is stellate, rarely punctiform. 

 Striations invisible. Starch fairly homogeneous. 



Cajanus indicus (Pigeon Pea). — Seeds rich in starch. The shape of 

 the grains is fairly uniform, whilst their size is very variable. Polariza- 

 tion is general and well marked. The hilum is linear, very rarely 

 punctiform and more often branched; numerous grains are found in 

 which' no hdlum can be seen. The striations are only visible in a few 

 rare grains ; they are not very close together. Starch only slightly 

 homogeneous. 



Canavalia ensiformis (Jack Bean). — Seeds rich in starch. The 

 shape of the grains is fairly uniform, whilst their dimensions vary; the 



