18 BOTANICAL GAZETTE [JANUARY 
may explain the so-called hybrids obtained by VAN T1EGHEM. In 
most cases fertilization occurs in the usual way. 
' 6. Both suspensors and young embryos may unite, so that from 
five fertilized eggs there may come one to five embryos. In the 
mature seed, as found in nature, there is one embryo with a 
single cotyledon. 
THE UNIVERSITY OF CHICAGO 
LITERATURE CITED 
1. Dyer, W. T., TuIsTLETON, Cycadaceae, in Biologia Centrali-Americana. 
Botany 3:190-195. 1882-1886. 
2. EICHLER, A. W., Ein neues Dioon. Gartenflora 2:411-413. 1883. 
3. CHAMBERLAIN, C. J., The adult cycad trunk. Bor. Gaz. 52: 81-104. 
jigs. 20. 191. 
: , Spermatogenesis in Dioon edule. Bort. Gaz. 27:215-236. pls. 
15-18. 0. 
5. WEBBER, H. J., Spermatogenesis and fecundation of Zamia. U.S. Dept. 
of Agric., Bur. Pl. Ind., Bull. No. 2. pp. 100. ls. 7 I. 
6. IKENO, S., Tineetcachunsion iiber die cistteloue der Geschlechtsorgane 
und die Vorgang der Befruchtung bei Cycas revoluta. Jahrb. Wiss. Bot. 
322557602. pls. 8-10. 18098. 
7. CALDWELL, O. W., Microcycas calocoma. Bot. Gaz. 44:118-141. pls. 
I0-I3. 1907. 
8. Mrvakk, K., Ueber die eae von Cycas revoluta. Ber. Deutsch. 
Bot. Gosells. 24:78-83. pls. 6. 
9. CHAMBERLAIN, C. J., The om aia female gametophyte of Dioon. Bort. 
GAZ. 42:321-358. pls. 13-15. 1 
. WARMING, E., Recherches et yehiarques sur les cycadées. Oversigter 
Vidensk. Selsk. Forh. 1877. 
11. CHAMBERLAIN, C. J., Oogenesis in Pinus Laricio. Bot. Gaz. 2'7: 268-280. 
pls. 4-6. 1899. 
12. IKENO, S., Contribution 4 l’édule de la fécundation chez le Ginkgo biloba. 
Ann. Sci. Nat. Bot. 138:305-318. pis. 2, 3. 1901. 
13. VAN TIEGHEM, Pu., Recherches sur le symétrie de structure des plantes 
vasculaire. Ann. Sci. Nat. Bot. 135:1-314. pls. 3-8. 1870. 
14. ANGELA, SISTER HELEN, The embryo of Ceratozamia; a physiological 
study. Bort. Gaz. 45:412-416. figs. 7. 1908. 
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