ALDEN: LIFE HISTORY OF UVULARIA SESSILIFOLIA 445 
4. The primary sporogenous cells give rise to several micro- 
spore mother cells which are found mature in the middle of 
September. 
5. The divisions of the microspore mother cells take place in 
October and show the usual tetrads. The winter is thus passed 
with microspores fully formed. 
6. In the latter part of April the microspore divides to form 
the generative and the tube nuclei. The division of the former 
probably occurs after the shedding of the pollen. 
7. The archesporium of the megasporangium is not differ- 
entiated till early March and consists of a single hypodermal cell, 
the adjacent cells showing gradations in size and characteristics 
of potential archesporial cells. 
8. The archesporium does not divide to form a primary wall 
cell and primary sporogenous cell but functions directly as the 
megaspore mother cell. It reaches maturity about the middle of 
pril. 
9. The reduction division of the megaspore mother cell takes 
place the last week of April. . 
10. Two megaspores are found about one week later. 
CotumBia University. 
LITERATURE CITED 
1. Duggar, B. M. Studies in the development of the pollen grain in 
Symplocarpus foetidus and Peltandra undulata. Bot. Gazette 29: 
bl. 1, 2. 1900 
2. Smith, Arma. Abortive flower buds of Trillium. Bot. Gazette 22: 
402-403. 18096. 
. Chamberlain, C. J. Winter characters of certain sporangia. Bot. 
Gazette 25: 124-128. pl. 11. 1898. 
. Chamberlain, C. J. Contribution to the life history of Salix. Bot. 
Gazette 23: 147-179. pl. 12,18. 1897. 
- Moore, Emmeline. The study of winter buds with reference to 
their growth and leaf content. Bull. Torrey Club 36: 117-145. 
bl. 9-11. 27 Mr 1909. 
- Coulter, J. M., & Chamberlain, C. J. Morphology of angio- 
Sperms. 1909. 
Vesque, J. Développement du sac embryonnaire des Phanerogames 
angiospermes. Ann. Sci. Nat. Bot. VI. 6: 237-285. pl. 11-16. 
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