STRUCTURE.] FORAMEN. 399 



same genus (Euonymus) both pendent and erect ovules at 

 the same time, investigated the history of the circumstance 

 and thus discovered the law, that the raphe invariably passes, 

 along the side of the ovule, turned towards the placenta; that 

 in the pendulous ovules of Euonymus this is not the case, but 

 that they become erect ovules, if we suppose the raphe to be 

 brought into the right position ; and that, therefore, the ovules 

 of this plant are only curved downwards, having been, in 

 reality, erect. The correctness of this statement is confirmed 

 by tracing the development of the parts. Crowfoots (Ranun- 

 culacese) offer some remarkable examples of the same kind. 

 The one-seeded plants of this family have been divided by 

 the difference of pendent and erect ovules into Ranunculese 

 and Anemoiiese ; and botanists have imagined so important 

 a distinction really to exist, even between plants so nearly 

 allied to each other. But in these two divisions of Crow- 

 foots the ovule is, when young, exactly the same, being 

 ascending and anatropal. At a subsequent period the ovary 

 either grows exclusively at its point, when we have an erect 

 anatropal ovule, or the ovary expands downwards below the 

 ovule, which then curves from the placenta downwards and 

 becomes spuriously pendulous and anatropal with the raphe 

 turned from the placenta. In several cases no difference is 

 perceptible at the time of flowering (for instance between 

 Ranunculus and Myosurus) ; and in others the intermediate 

 states run so gradually together, that the difference alluded to 

 is wholly unfit to be made a ground of division. But when the 

 seeds are ripe it really does afford a well-defined distinctive 



character." 







It has also been stated that the passage through the pri- 

 mine and secundine is called the foramen; or the exostome, 

 when speaking of that of the primine ; and the endostome, in 

 speaking of the secundine. Upon these Mirbel remarks : 

 " These two orifices are at first very minute, but they gradu- 

 ally enlarge ; and, when they have arrived at the maximum 

 of dilatation they can attain, they contract and close up. 

 This maximum of dilatation is so considerable in a great 

 number of species, in proportion to the size of the ovule, 



