IN THE tropics: III. 129 



A closely similar series of experiments, in which somewhat 

 larger numbers of individuals were dealt with, will be found 

 described in the second part of this paper. 



4. INDENTATION OF GRAINS. 



It has already been pointed out that, when the indented type 

 of corn was crossed with a smooth variety, the grains pro- 

 duced showed no change from the shape characteristic of 

 the seed parent — there is no effect of such a kind as to be visible 

 as " xenia." In later generations therefore this character 

 can be treated as a plant character, all the grains on the same 

 plant being alike, except that the grains near the apex of a 

 cob are generally less indented than the lower ones. 



F , from the cross smooth x indented shows a strictly inter- 

 mediate character, the grains so produced being of the type 

 known as half-dent. 



In F 2 , arising from the intercrossing of F, plants, a high 

 degree of variability makes its appearance ; and plants were 

 obtained which closely approached the fully indented type 

 as well as others in which the grains were almost completely 

 smooth, but the great majority of plants were intermediate, 

 showing every kind of blending between the two original 

 types. 



On crossing F, with the full-dent type, every gradation 

 between the full-dent and the half-dent types were obtained in 

 V 2 . 



Without making pollinations between individual plants it 

 therefore appears impossible to decide whether Mendel's law 

 is or is not followed in this case. 



Biffen finds that in wheats the characters hard and soft 

 endosperms (which may be compared with the flinty and 

 indented characters respectively) on crossing show dominance 

 of the hard type in F, (plants), and Mendelian segregation in 

 Ff (of plants — F 3 of grains). This perhaps renders it the more 

 likely that there is segregation of the corresponding characters 



