1891.] Relationships of the Archegoniata. 333 



Kny 1 claims a distinct origin for the two divisions of the 

 angiosperms. He says, "The two principal divisions of 

 the angiosperms, dicotyledons and monocotyledons, repre- 

 sent two great independent lines of development, whose origin 

 reaches at least as far back as the vascular cryptogams, if not 

 lower." He is inclined with Strasburger to connect conifers 

 and dicotyledons with the Lycopodinea^, and would derive 

 the monocotyledons directly from the ferns. 



Prantl's 2 views are much the same as Kny's, except that 

 possibly a part of the dicotyledons have a common origin 

 with the monocotyledons. 



From the evidence at present available, both of embryology 

 and palaeontology, the assumption of a separate origin for the 

 two groups of the angiosperms is certainly unwarrantable. 

 In all forms yet investigated, the uniformity in the essential 

 structure of the flowers, and especially the development of 

 the embryo-sac, points unmistakably to a common origin. It 

 may be that further investigations upon the lower members 

 of both groups may modify this view, but that such extraor- 

 dinary correspondence as exists in the formation of the em- 

 bryo-sac, the structure of the egg apparatus, the fusion of the 

 endosperm nuclei, etc., could have arisen independently in 

 the two groups is inconceivable. 



On the other hand, the evidence for a direct connection of 

 gymnosperms and angiosperms, is not entirely convincing, 

 and the possibility of a separate origin for these two groups 

 is by no means unlikely — nay, seems quite probable. 



Whether the origin of the angiosperms is to be looked for 

 directly from the Filicinese, through such forms as /socles, or 

 from forms higher up like the cycads, can only be satis- % 

 factorily answered after many forms have been thoroughly 

 studied. As yet our knowledge of the embryology of the 

 cycads and the simplest angiosperms is too incomplete to 

 make an answer to this question more than a mere conjecture. 



Palo Alto, California. 



1 Entwickelung der Parkeriaceen, p. 61 

 * Hymenophyllaceae, p. 68. 



