6 ON SEEDLINGS 



In a third category the ovule itself is straight, but it stands 

 as it were at right angles to the base of attachment. These 

 are called lialf-anatropous or half-reversed. 



Lastly, in a very large number in fact the largest 

 the ovule is quite inverted on its base ; the funicle, or stalk, 

 growing with its curvature, and forming a sort of ridge 

 or raphe, which is very conspicuous in the ovule, but gradually 

 becomes less and less apparent, finally becoming merged in 

 the seed-coat. The chalaza is thus carried right away from 

 the hilum to the opposite end, and the whole ovule or seed 

 is reversed, so that the true base is removed from, and the 

 true apex brought close to, the point of union with the 

 ovary. Such are called anatropous or reversed. 



Now this seems a very curious and roundabout arrange- 

 ment. It is described in all works on general Botany, but 

 those which I have seen do not give any explanation of its 

 object or purpose. I will for the moment omit any consi- 

 deration of campylotropous and half-anatropous seeds, and 

 confine myself to orthotropous and anatropous forms. 



In most orthotropous species, as for instance in the Buck- 

 wheat, the ovule is straight, upright, and attached by its base 

 to the funicle and base of the ovary. At the free end is 

 the micropyle, and immediately below it the egg-cell, which, 

 when fertilised by the pollen, becomes the rudiment or embryo 

 of the future plant. When the pollen falls on the stigma it 

 soon pushes out a little tube, which rapidly elongates, passes 

 into the cavity of the ovary, and entering the micropyle of 

 the ovule fertilises it. 



But ovules thus constituted are, as I have already men- 

 tioned, exceptional. In a great many plants the ovule, instead 

 of being upright and attached to the base of the ovary, is, on 

 the contrary, attached to the summit and pendent. Now in a 

 pendent orthotropous ovule the micropyle is turned away from 

 the pollen-tube, and the object and effect of the ovule being 

 reversed or anatropous is to bring it back into a convenient 

 position for fertilisation. So also, when there are many 

 ovules, the result of the anatropous arrangement is again to 

 bring the micropyle into a suitable position. 



The structure and arrangement of the ovule have been the 



