of Gentiana campestris. 391 



structure. Professor Henslow has recorded instances in the 

 mignonette of the ovules being transformed into leaves, either 

 solitary or rolled round an axis, of which the nucleus is the ter- 

 mination. Others have maintained that in certain families the 

 ovules are parts of the carpellary leaves themselves. In confir- 

 mation of this, M. Ad. Brongniart has published an account of a 

 monstrosity of Delphinium datum. On the borders of the carpels 

 were observed all states of transition from lateral trifid lobes of 

 the leaf to true ovules. The lateral teeth of these lobules became 

 atrophied ; the middle part was hollowed and curved upwards and 

 inwards in the form of a hood, so as to constitute the primine. 

 The nucleus was described as originating from a cellular excres- 

 cence or papilla situated on the upper surface, upon the median 

 nerve of each lobe a little below its summit. M. Brongniart con- 

 siders it a new production, a cellular papilla, developed on the 

 superior face of the middle lobe of the leaflet, and in the cavity 

 which the latter had formed. Some of the ovules observed in 

 the gentian appeared at first to confirm this opinion. In exa- 

 mining its merits, however, it appears necessary to take into ac- 

 count two circumstances, the order of development of the ovules, 

 and that of their individual parts. From careful examinations 

 made some years ago, I have been convinced that in some carpels 

 whose ovules are numerous, the order of development is from the 

 base to the apex. In very early stages of the carpel, the ovules are 

 confined to the lower part alone, there being no trace of them to- 

 ward the upper portion of the placenta. At a more advanced 

 stage they occur through the greater part of its extent, but still 

 there is a very evident difference (previous to impregnation) be- 

 tween the progress made by ovules from the base of a placenta, 

 and those nearer to its apex ; this is obvious to the unassisted 

 eye in regard to the development of the membranes, but actual 

 measurement removes all doubt. The Viola canina may be men- 

 tioned as an example within the reach of those who choose to 

 investigate this matter. In regard to the second point, viz. the 

 order of development of the individual parts (reference is here 

 made to the three outer membranes only), it is unnecessary to say 

 much. In the young capsules of the violet already alluded to, 

 it will be found that each ovule first appears toward the lower 

 part of the placenta as a cellular papilla, the nucleus ; the secun- 

 dine soon makes its appearance as a cellular ring around the base 

 of the former ; and lastly, another ring, the rudiment of the pri- 

 mine, appears on the outside of the secundine ; the outer mem- 

 brane, however, becomes rapidly developed, inclosing and con- 

 cealing the other two. It may be also worthy of notice, that the 

 ovules make their appearance while the carpel is still entirely 

 cellular, there being no trace of any vascular tissue till a more 



