THE AXGIOSPERMAE 1221 



of ontogenetic evidence provided by members of the higher Monocotyledons. 

 This has led him to the view that there are no carpels involved in the 

 formation of an inferior ovary and that the invagination of the receptacular 

 apex which gives rise to the loculi has a surface which is a continuous 

 potential megasporangium. Continuous ovulation is, however, never 

 achieved and ovulation occurs only on lines of nutritive advantage, which are 

 considered to be the placental emergences. 



From this theory of " acarpy " the author advances to a much wider 

 generalization which might almost be called " ananthy " since he proposes 

 to reduce the fertile organs of all flowers, both stamens and carpels, to the 

 status of sporangiferous emergences. The flower becomes, in his eyes, 

 only a specialized heterosporous strobilus, of which the lower part is 

 sterilized and the upper part is potentially completely sporogenous, but in 

 actuality is limited by physiological causes to the production of sporangia on 

 localized emergences. Whether the strobilar axis develops as a cone or as a 

 cup is immaterial and depends on whether growth is localized at the apex or 

 is predominantly " toral ", that is, intercalary. 



The word " torus " used by McLean Thompson and by many other 

 writers on floral morphology would be better dropped, since it has been 

 used in several senses (see p. 1129). 



The revolutionary views of McLean Thompson have not, as yet, com- 

 mended themselves widely to morphologists; for they are confronted by 

 many contrary indications as well as the general coherency of plan which 

 comparative morphology reveals. What is involved is not so much the 

 abolition of the word " carpel ", since structures called by that name do 

 exist as recognizable entities, but rather the abolition of the theoretical halo 

 surrounding the structure, and its acceptance instead as siii generis, some- 

 thing without homologies and without a history. The abolition of the idea 

 of the carpel can only with difliculty be limited to the inferior ovary, with 

 which we are immediately concerned, since ontogeny and comparative 

 morphology show that carpel-like structures are, at least in some cases, 

 formed inside the supposed invagination of the receptacle which becomes 

 the ovary in epigynous flowers (Fig. 1188). There are so many resem- 

 blances between the carpels in the hypogynous and epigynous forms within 

 single groups, such as the Liliales, that logically the existence of carpels 

 ought to be accepted in both, or denied in both. As regards the inferior 

 ovary, however, McLean Thompson does claim that even the structures 

 elsewhere known under the name of carpels do not exist but are simulated 

 by axial emergences behaving as placentae. His position is that it is only in 

 superior gynoecia that the emergences assume the form known as carpellary. 

 The idea of ring-like " toral " growth of the floral axis, as postulated in 

 some of the above theories of epigyny, rests on little besides assumption. 

 It is based upon the hypothesis that if the upward growth of the vegetative 

 point be checked, the " growth energy " of the axis will find expression 

 in lateral expansion, producing a ring-like emergence, which does not 

 continue to expand laterally, but turns upward to form a cup enclosing the 



