BILLINGS: EMBRYO NUTRITION IN LABIATE. 83 



Gentianese. The two have since been raised to family rank, 

 probably for other reasons, yet it is interesting to note that 

 the structure of the ovule justified the wisdom of the change. 

 In this way can a study of sporangial, gametophytic and em- 

 bryonic structures be of service in establishing more natural 

 relationships and groupings. 



LITERATURE CITED. 



1. F. H. Billings. Beitrage zur Kenntniss der Samenentwickelung. 



Flora Bd., 88 Heft 3, 1901. 



2. M. Treub. Notes sur I'embryogenie de quelques Orchidees, Natur- 



kund. Verhandl. Konigl. Akad. Deel. 21, 1879. 



3. F. E. Lloyd. The comparative embryology of the Rubiaceae. Mem- 



oirs of the Torrey Botanical Club, vol. VIII, No. 1, Pt. 2, 1902. 



4. K. GoEBEL. Organographie der Pflanzen, vol. II, Jena, 1901. 



5. E. SCHMID. Beitrage zur Entwickelungs-geschichte der Scrophulari- 



aceae, Zurich, 1906. 



6. G. P. Balicka-Iwanowska. Contribution a I'etude du sac embryon- 



naire chez certaines Gamopetales, Flora 86, 47-71, 1899. 



