1220 A TEXTBOOK OF THEORETICAL BOTANY 



being reduced to little more than their stigmas, roofing in the cavity. An 

 amplification of this theory regarded the carpellary placentae as extending 

 downwards into the cavity or, in plurilocular inferior ovaries, as having 

 remained in the form of an axial column in the cavity, while the dorsal parts 

 of the carpel had been elevated by the upgrowth of the cup. This was the 

 position maintained by Sachs. Its influence gave rise to much controversy 

 regarding the nature of the placentae, as to whether they were of carpellary 

 or axial nature in various cases. 



The lack of any structural sign of compound nature, which it must be 

 admitted is the case in most toral cups, is not conclusive against their 

 origin by cohesion, since there are structures where cohesion must have 

 taken place, where there is equally no sign of it observable. Such instances 

 are the calycular cap which covers the bud in Eiipomatia, later shed by 

 circumscissile dehiscence, and the naked portion of the spadix in Arum 

 which Diels has shown to be formed by the complete cohesion of flower 

 rudiments, the individuality of which is entirely lost in a uniform surface. 



There seems to be a strong case for adnation in Doryanthes excelsa 

 (Amaryllidaceae), where the carpels arise on the floor of a slight depression 

 in the receptacle and are not overgrown until a comparatively late stage in 

 their development. In the floral cup which eventually surrounds them the 

 stamen and perianth traces are separate from the carpel traces all the way 

 down. There are no distinctively axial features in the cup. The carpels 

 have their own epidermis and remain distinct. The degree of union is slight 

 both between the carpels and with the cup, to which they become adnate. 



We may pass over the theories which regarded the inferior ovary as an 

 organ siti generis, that is to say without homologies, since they are 

 involved with the view of the flower as an entirely novel structure, proposed 

 by Gregoire, which we have dealt with earlier (see p. 1123). These views 

 are related to the " acarpous " theory of McLean Thompson, which we shall 

 speak of presently. 



Another view of some antiquity, rivalling that of Schleiden, regarded the 

 axial cup as having arisen around the gynoecium, which was enclosed by it, 

 the carpels remaining intact but enclosed. The gynoecium, therefore, in 

 this case, did not difl"er essentially from a superior gynoecium, and as in the 

 latter case, there might, or might not, in difl^erent genera, be an extension of 

 the axis upward in the centre of the carpellary whorl. 



This theory is associated with the name of Celakovsky and von Goebel. 

 The extent of enclosure of the carpels might be variable and while, in 

 general, only the styles, if any, and the stigmas remain free, there are 

 examples such as Alstroemeria and Moraea in which there is a substantial 

 part of the top of the ovary left unenclosed. Of course, such variations 

 might also be expected under the appendicular theory. 



This theory eventually held the field and has only been challenged, in 

 recent years, by the revival of the appendicular theory of de Candolle, by 

 Eames. 



Lastly, there is the theory advanced by McLean Thompson on the basis 



