Igto] SHATTUCK—HETEROSPORY IN MARSILIA 37 
develop a perinium, but enlarged considerably and became gorged 
with starch. 
10. In the normal plants, and in all cultures, a close examination 
reveals a homosporous tendency, shown by the formation of micro- 
spores in the megasporangia, especially in those most distant from the 
nutritive supply. 
11. Marsilia may be made to repeat, under culture, all the phases 
in the development of heterospory reported by WILLIAMSON and 
Scort for Calamostachys Binneyana and C. Casheana, icone in addi- 
tion to produce a megaspore of intermediate size. 
Acknowledgments are due to Professor JoHN M. CouLTeR and to 
Professor CHARLES J. CHAMBERLAIN, under whose direction this 
work was carried on. 
UNIVERsITy oF IDAHO 
Moscow 
LITERATURE CITED 
1. Bucutien, O., Entwickelungsgeschichte des Prothallium von Equisetum. 
Bibliotheca Botanica a 
- Bower, F. O., The origin of the land flora 551, 704. 
. Camppett, D. H., Structure and development xe mosses and ferns 447, 
453- gos. 
4. , Affinities of the Ophioglossaceae and Marsiliaceae. Amer. Nat. 
38: 761-775. 1904. 
5: » Die Entwickelung des Embryosackes von — pellucida 
Kunth. Ber. Deutsch. Bot. Gesells. 1'7:452-456. pl. 31. 1899. 
- Cuampertaty, C. J., The rae ge sac of Aster pease Bor. GAZETTE 
20: 205-212. pls. 15, 16. 5: 
- Courter, J. M., Gann: to the life history of Lilium philadelphicum. 
OT. GAZETTE 23: 412-422. pls. 32-34. 1897. 
Ne sarana Baskestadices i rs lite history of Ranunculus. Bot. GAZETTE 
25: 73-88. pls. 4-7. 1808. 
9. Crocker, Wa., Réle of seed coats in delayed germination. Bot. GAZETTE 
42: :265-291, sisi 
- Ernst, A,, Beitriage zur Kenntniss der Entwickelung des Embryosackes 
und des Embryo “Mitnaten ss von Tulipa Gesneriana L. Flora 88: 
37-77. pls. 4-8. 1 
GoEBEL, K. Sega 22479. 1905. 
geek. ees , Outlines of classification and special morphology 257. 1887. 
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