Feb., 1904.] Nymphaeacae and Helobiae. 89 



during the life cycle must be taken into account, otherwise the 

 result will be largeh' artificial. As intimated above, the writer, 

 through paleontological studies, came to the conclusion a number 

 of years ago that Monocotyls did not come from Dicotyls nor 

 Dicotyls from Monocotyls ; that the Angiosperms do not represent 

 two sharply defined classes, but that there are a number of lines 

 of development from some common stock ; and that on this 

 account there are frequent independent duplications of important 

 characters in quite distinct series of forms. According to the 

 views expressed above the relationship of the groups under dis- 

 cussion may be represented as shown in the diagram ( Text Fig. 2 ) . 

 Since lists of the important literature have recently been given 

 in a number of papers, it is not necessary to add an extensive 

 bibliography here. 



1. Lyon, H. L. Observations 011 the Embryogeny of Neluinbo. Minn. 



Bot. Stndies 2 : 643-655. 1891. 



2. Cook, M. T. Development of the Embryo-sac and Embryo of Castalia 



odorata and Nyniphaea advena. Bull. Torr. Bot. Club 24: 211-220. 

 1902. 



3. Conrad, H. S. Note on the Embryo of Nyniphaea. Science 15 : 316. 



1902. 



4. CampbeIvTv, D. H. On the Affinities of Certain Anomalous Dicotyle- 



dones. Amer. Nat. 36 : 7-12. 1902. 



EXPLANATION OF PI.ATKS V-VII. 



The diagrams represent typical flowers selected from a series of 

 variable types and show the actual number and position of the 

 floral organs. The other figures were drawn with the aid of an 

 Abbe camera. 



PI.ATE v. 



Fig. I. Section of vascular bundle from the peduncle of Nelumbo lutea. 



Fig. 2. Diagram of flower of Alisma plantago. 



Fig. 3. Diagram of carpellate flower of Sagittaria rigida. 



Fig. 4. Diagram of staminate flower of Sagittaria rigida. 



I'ig. 5. Diagram of carpellate flower of Sagittaria latifolia. 



Fig. 6. Diagram of staminate flower of Sagittaria latifolia. 



PLATE VI. 



Diagram of flower of Cabomba carol iniana. 

 Diagram of flower of Brasenia purpurea. 

 Diagram of flower of Potamogeton natans. 

 Diagram of flower of Nyniphaea advena. 

 Diagram of flower of Castalia odorata. 

 Diagram of flower of Castalia tuberosa. 

 Diagram of flower of Nelumbo lutea. 



Fig. 7 

 Fig. 8 

 Fig. 9 

 Fig. 10 

 Fig. II 

 Fig. 12 



PLATE VII. 



F'ig. 14. Young embryo of Nytrphaea advena. 



F'ig. 15. The same embryo as in Fig. 14, back view. 



Fig. 16. Young embryo of Castalia odorata. 



Fig. 17. Older embryo of Castalia odorata, upper side. 



Fig. 18. The same embryo as in Fig. 17, under side. 



F"ig. 19. Still further developed embryo of Castalia odorata, showing 

 " Dicotyl " appearance. 



