1912] SHARP— ORCHID EMBRYO SAC 383 



To Professor Duncan S. Johnson are due acknowledgments for 



many valuable suggestions during the progress of the work. The 

 writer is also indebted to Mr. William Harris for placing at his 

 disposal material in the Hope and Castleton Botanic Gardens. 



The University of Chicago 



LITERATURE CITED 



1. Brown, W. H., The embryo sac of Habenaria. Box. Gaz. 48:241-250. 

 figs. 12. 1909. 



2. Brown, W. H., and Sharp, L. W., The embryo sac of Epipactis. Box. 

 Gaz. 52: 439-452. pi. 10. 191 1. 



3. Campbell, D. H., The embryo sac of Pandanus. Bull. Torr. Bot. Club 



36:205-220. pis. 16, 17. 1909. 



4^ Chamberlain, C. J., Contribution to the life history of Salix. Box. Gaz. 

 23:147-179. pis. 12-18. 1897. 



5- Karsxen, G., tJber die Entwicklung der weiblichen Bliithen bei einigen 

 Juglandaceen. Flora 90:316-333. pi. 12. 1902. 



6. Leavixx, R. G., Notes on the embryology of some New England orchids. 

 Rhodora 3 : 202-205. pi. 33. 1901. 



7. Pace, Lula, Fertilization in Cypripedium. Box. Gaz. 44 : 3 53-37 4. pis. 

 24-27. 1908. 



8- , The gametophytes of Calopogon. Box. Gaz. 48: 126-137. pis. 7-g. 



1909. 



<>• Sxrasburger, E., tlber Befruchtung und Zelltheilung. 1878. 

 10. Ward, H. Marshall, On the embryo sac and development of Gytnnadenia 

 conopsea. Quart. Jour. Micr. Sci. 20:1-18. pis. i-j, 1880. 



EXPLANATION OF PLATES XXI-XXIII 



All figures were drawn with the aid of an Abbe camera lucida, and shov 

 magnifications as follows: figs, i-iq, X1200; figs. 16-18, X295; figs. 19-24 



200 



fig 



PLATE XXI 



Epidendrum variegatum Hook. 



Fig. i. — Synapsis in megaspore mother cell. 



Inner daughter cell dividing; oute 

 Fig. 3. — Functioning megaspore: outer d 

 disorganized. 



• • 



megaspore 



Fig. 4.— Two-nucleate embryo sac: no wall on lingering spindle fibers. 



