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1907] SMITH—TRUNK AND MICROSPORANGIUM OF CYCADS 201 
villosus 26,000. Therefore the output per sporangium in these 
species increases according to the number of sporangia upon the 
sporophyll. 
16. The pollen grains are three-celled at the time of shedding, 
the cells being the prothallial, the generative, and the tube. 
This investigation was carried on under the direction of Professor 
Joun M. Coutrer and Dr. C. J. CHAMBERLAIN, of the University 
of Chicago. 
SMITH COLLEGE 
Northampton, Mass. 
LITERATURE CITED 
I. Mique, F. A. W., Monographia Cycadearum. 1842 
2. Karsten, H., Cnuancutasbiecie Babrachitinsiees der Zomia muricata, Abh, 
Akad. Berlin. pp. 27. pls. 3. 1857. 
3- DeWary, A., Notizen iiber die Bliite einiger Cycadeen. Bot. Zeit. 28: 
574-577- 1870. 
4. Juranyt, L., Ueber den Bau und die Entwickelung des Pollens bei Ceratoza- 
mia longifolia Miq. Jahrb. Wiss. Bot. 8:382~-400. pls. 31-34. 1872. 
5- Braun, A., Die Frage nach der Gymnospermie der Cycadeen. Monatsber. 
k. Akad. Wiss. Berlin. 241-377. 1875. 
6. Warmine, E., Recherches et remarques sur les Cycadées. Oversigter over 
d. K. D. Vidensk. Selsk. Forh. 1877. 
7: , Contributions 4 Phistoire naturelle des Cycadées. Ibid. 1879. 
8. Tarn, M., Recherches sur les Cycadées. Ann. Jard. Bot. peusexs 
32-53. pls. 1-7, 1881. 
9. rial J., Textbook of asacae 4 1882. 
Io. DeBary, A., e ti y of th ps4 tati 5 fth pl oS 
and ny English translation. 1884. 
II. GoEBEL, K., Outlines of classification and special morphology. English 
ieialatcn. 1887. 
12. GuricnarD, L., Observations sur le pollen des Cycadées. Jour. Botanique 
3*222-237. 
13. OvErRTON, E., Ueber die Reduction der ss ss in den Kernen der 
nzen. Nistuct Gesells. Zurich 38:— 
14. Encter, A. und Prantt, K., Die natirlichen ‘Pflanzenfamilien rel 
15. Bower, F. O., Studies in the morphology o Ii. 
Marattiaceae. “Phil. Trans. Roy. Soc. Laide. 189: 35-81. “pls. 7-11. 1897. 
16. Lanc, W. H., Studies in the development and morphology of cycadean 
sporangia. I. The microsporangia of Stangeria paradoxa. Annals of 
Botany 11: 421-438. pl. 22. 1897. 
17. Scott, D. H., Studies in fossil botany. 1900. 
