1906] CHAMBERLAIN—OVULE OF DIOON 355 
ment is probably double in nature, the outer fleshy layer representing 
the outer integument. 
6. Only a small portion of the nucellus is free from the integument. 
7. One vascular bundle passes from the sporophyll toward each 
ovule. Before entering the ovule the bundle forks, one branch form- 
ing the continuously branching system of the inner fleshy layer of the 
integument, and the other forming the slightly branched system of 
the outer fleshy layer. 
. The megaspore membrane varies in thickness from 3-4.5 # in 
young ovules to g—10 # in mature seeds. 
9. The number of archegonia varies from one to ten, with four 
and five as the most frequent numbers. The archegonium initial 
appears in October; the division into neck and central cell takes 
place almost immediately after; the mitosis which forms the ventral 
canal nucleus and egg nucleus takes place during the next May. 
10. The central cell and egg during earlier stages receive food 
substances by the ordinary method of nutrition, but later receive 
food material through haustorial projections from the egg which are 
in direct contact with the cytoplasm of the jacket cells. 
11. There are twelve chromosomes, in the egg nucleus, which is 
the largest one yet known in plants. 
THE UNIVERSITY OF CHICAGO. 
LITERATURE CITED. 
_ 1. Biacxman, V. H., On the cytological features of fertilization and related 
features in eine sylvestris L. Phil. Trans. Roy. Soc. London B. 190: 
395-426. pls. 12-14. 1808. 
- CHAMBERLAIN, C. J., Oogenesis in Pinus Laricip. Bot. GAzeTTE 27: 
268-280. pls. 4-6. 1899. 
- Coxer, W. C., Notes on the gametophytes and embryo of Podocarpus. 
Bor. Gazerre 33:89-107. pls. 5-8. 1902. 
Couter, J. M., Notes on the fertilization and embryogeny of Conifers. 
Bor. Gacerts 23:40-43. pl. 6. 1897. 
- Courter, J. M., and CHAMBERLAIN, C. J., The embryogeny of Zamia. 
Bor. Gazerre 35:184-194. pls. 6-8. 1903. 
- Coutrer, J. M.; and Lanp, W. J. G., The genie and embryo of 
Torreya taxifolia. Bor. GAZETTE 39:161-178. pls. I-3. 1905. 
; apa eee Marearet C., Contributions to the cae of the life history 
of Pinus. Proc. Wash. Acad. Sci. 6:1-202. pls. 2-24. 1904. 
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