THE ABORTION OF OVULES 345 



hint that in the form of a fruit we have the history of the 

 ovule rather than of the seed. 



Regarding the beading of legumes many fruits supplied 

 evidence both direct and indirect. Not only was special 

 appeal made to characteristic moniliform pods like those of 

 Sophora and Erythrina and to the less marked, though normal, 

 contractions of the legumes of Albizzia^ but help was also 

 received from legumes like those of Poinciana regia^ where the 

 contraction of the pod is the exception and not the rule, and 

 from pods like those of Vicia and Ulex, where the symmetry 

 of the fruit is not afFected by the failure of ovules and of very 

 young seeds. The indications again of fruits of other types, 

 like those of /m, gave valuable data in this connection. 

 Scarcely a fruit examined failed to assist in the elucidation of 

 the problem. One of the earliest notes in my journal relating 

 to this subject was to the effect that there was evidently a very 

 early stage of ovule-abortion in the case of pods of Erythrina 

 corallodendron which expressed itself in the narrowest constric- 

 tions of the fruit, but left no trace of the ovule itself. This 

 has served to lighten up the background of the inquiry from 

 the commencement to the end. 



I made a special study of the legumes of Vicia sativa and The failure 



V. sepium as concerns the abortion of ovules and the failure vi^iTsltiva 



of young seeds. In the first case the legumes are lonp- and ^"^ . 



T 1 J 1 1 , , ■ 1 V- sepium. 



narrow. In the second case they are short and relatively 



broad. The pods of Vicia sativa average 43 or 44 millimetres 

 in length and about 5 millimetres in breadth, and possess as 

 a rule eleven mature seeds and one aborted ovule or un- 

 developed seed. The pods of Vicia sepium average about 3 1 

 millimetres in length (range 25 to 2>^ millimetres) and 6 

 millimetres in breadth, four or five seeds being usually 

 matured. In both species the average number of ovules in 

 the flower is about the same, namely, twelve, the range being 

 ten to sixteen in both plants. 



With both species all the ovules begin to enlarge and to 

 turn green after fertilisation of the ovary. At first about 0*3 



