388 VIEWS OF BKOWN AND LINK. [BOOK i. 



Primula, and Cortusa, are numerous and arranged spirally." 

 (See Annals of Natural History, xiv. 406.) 



This evidence is irresistible, and has led to a more careful 

 examination of the origin of the placenta, the result of which 

 is, that, undoubtedly, in a very large number of cases, it is 

 certainly an expansion or extension of the axis, and by no 

 means a natural process. This is easily shown in Cranesbills 

 (Geraniacese), Tutsans (Hypericacese), Bindweeds (Convol- 

 vulacese), Oxalids, Mallow worts, Myrtleblooms (Myrtacese), 

 and many other natural orders. Brown, however, clings to 

 the sutural theory : 



"I have assumed," he says, "that ovules belong to the 

 transformed leaf or carpel, and are not derived from processes 

 of the axis united with it, as several eminent botanists have 

 lately supposed. That the placentae and ovula really belong 

 to the carpel alone is at least manifest in all cases where 

 stamina are changed into pistilla. To such monstrosities I 

 have long since referred, in my earliest observations on the 

 type of the female organ in phsenogamous plants, and since 

 more particularly in my paper on Rafflesia : the most remark- 

 able instances alluded to, in illustration of this point, being 

 Sempervivum tectorum, Salix oleifolia, and Cochlearia Armo- 

 racia, in all of which every gradation between the perfect 

 state of the anthera and its transformation into a complete 

 pistillum, is occasionally found." This is, however, no 

 answer to the evidence of Schleiden, Schykoffsky, and 

 Duchartre ; and has been thus disposed of by Link : 



"Such a general rule has always appeared to me, not 

 merely doubtful, but altogether incorrect. For when do 

 buds proceed from the margin of true leaves? A bundle of 

 vessels never runs to the margin, whence buds or young 

 shoots might proceed, and which would present the only 

 analogy to the bundle of vessels, from which the ovules in 

 the pericarp arise. If Bryophyllum calycinum be quoted, it 

 serves for a reply, that the buds do not grow from the margin, 

 but only in its neighbourhood, in the angle of the notch, 

 where numerous delicate nerves interlace. Or, if Phyllanthus 

 be adduced, we can easily reply, that here the so-called leaves 

 are only expanded petioles, as the little scale below them 



