202 BOTANICAL GAZETTE [MARCH 
LITERATURE CITED 
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, Winter conditions of ae serene ts Bor. Gaz. 25:124-128. 
pl. 11. 00 8. 
4. SHATTUCK, CHARLES H., A  . study of Ulmus americana. 
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SHOEMAKER, D. N., On the EBS of Hamamelis virginiana. Bot. 
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BENSON, MARGARET, Coatdbarwus to the embryology of the Amentiferae. 
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7. TrEUB, M., Sur les Casuarinées et leur place dans le systéme naturel. 
Ann. Jard. Bot. Buitenzorg 10:145-231. pls. 12-32. 1891. 
, reve, 1.C., — embryo sac of Casuarina stricta. Bot. Gaz. 36: 101-113. 
pl. 17. 190 
. KOERNT ag , Untersuchungen iiber die Entstehung und Entwickelung 
der Sisislorpane von Triticum mit besonderer Beriicksichtigung der Kern- 
theilung. Verhandl. Natur. Hist. Ver Preussen Rheinl. 53:149-185. 
3- 
sig 
oo 
1896. 
10. GUIGNARD, L., Recherches sur le sac embryonnaire des Phanérogames _ 
Angiospermes. Ann. Sci. Nat. Bot. VI. 13:136-109. pls. 3-7. 1882. 
11. Jounson, D. S., On the development of certain Piperaceae. Bot. GAZ. 
34:321-340. pls. 9, 10. 1902 
cs Pex, 1..C., A oo teeta ee of certain Asclepiadaceae. Bor. 
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Bor. Gaz. 30:1-11. pl. r. 1900. 
EXPLANATION OF PLATES XVII-XX 
All figures were made with an Abbé camera lucida. A Zeiss microscope 
was used with ocular 4 and objectives 2/3 and 2 mm 
Abbreviations: a, antipodals; em, endosperm; em, embryo; , nutritive 
layer; c, conducting tissue; 0, outer integument; 7, inner integument 
Fic. 1.—Portion of a longitudinal section of a stamen in winter condition; 
X 600. 
Fic. 2.—Similar portion of a stamen Feb. 16, showing the separation of 
the plates of spore mother cells and the breaking down of tapetal cells; 600. 
_ Fic. 3.—A diagram through the ovule when the embryo sac is mature, 
showing the position of the embryo sac and the great development of integu- 
ments; R 
