352 STUDIES IN SEEDS AND FRUITS 



ovules share at first in the results of the fertilisation of 

 the ovary ; and it is to those that fail early that the epithet 

 of " aborted " is applied.) It is the early failure of the 

 ovule that alone determines the contraction of the legume, 

 and it is the number of such contiguous ovules that deter- 

 mines its amount. 



The external form of the legume of Albi-zzia Lebbek there- 

 fore at once gives a clue as to the number of ovules that have 

 aborted early and the number that have advanced to the seed- 

 stage ; but it tells us nothing of whether the seed inside is 

 fully formed or only half or a third of the normal size, the 

 opening of the pod being required for that purpose. The 

 form of the pod, therefore, depends on the fate of the ovules 

 in an early stage of their history after the fertilisation of the 

 ovary. After that is determined the ultimate form of the pod 

 is fixed, and is not affected even if all the seeds fail before 

 attaining half their normal size. 



With the early failure of the ovules are connected, as before 

 remarked, the contractions of the pod, which may be so slight 

 as merely to give a sinuous margin to the fruit, or so marked 

 as to produce almost a beaded shape. The moniliform 

 tendency is displayed when the failure takes place in the body 

 of the fruit. When the ovules abort at the ends the pod 

 acquires tapering extremities. Now, as respects the narrowing 

 of the body of the fruit, I find that the extent of the contraction 

 depends on the number of contiguous ovules that fail. Thus 

 a typical many-seeded pod, 35 millimetres broad in the seeded 

 portion, has its width reduced to about 30 millimetres where a 

 single ovule fails, to about 25 millimetres where two con- 

 tiguous ovules abort, and to about 12 millimetres where three 

 or four ovules fail. As a rule, when the space between the 

 seeds is 1 2 to 1 5 millimetres broad there is no aborted ovule. 

 When the inter-seminal space amounts to from 20 to 22 

 millimetres in width there is a single aborted ovule. When it is 

 30 to 35 millimetres there are two contiguous aborted ovules ; 

 when 45 to 50 millimetres, three contiguous ovules, and so on. 



