Campbell : The embryo-sac of Pandanus 207 



fertilization, e. g,, Sparga7iiinn diwd s^v^vdX Araceae, or this increase 

 in number may take place before fertilization, as in certain grasses.* 

 Many Ranunculacae are also characterized by a large development 

 of the antipodal cells, which may become multi-nucleate, but ac- 

 cording to Mottier f the nuclear division is amitotic and is presum- 

 ably a secondary condition. The increase in the number of anti- 

 podals in the Compositae and some other sympetalous forms is 

 considered by Coulter J to be a secondary condition associated or 

 involved in the formation of a haustorial organ. 



In Pandanns there is an increased number of nuclei, /, e., 14 

 instead of 8, and to judge from the most advanced stages that were 

 met with, there is a failure to develop the definite structures of the 

 typical embryo-sac. It is possible an examination of older ma- 

 terial may show a development of further embryo-sac structures 

 before fertilization takes place. • 



The Pandanaceae, comprising thfe genera Pandanus and Frey- 

 chietia^ are confined entirely to the old world, being especially 

 abundant in the Malayan region, where they constitute a very 

 striking feature of the flora. One species of each genus extends 

 to the Hawaiian Islands. The Pandanaceae are usually considered 

 to be among the lowest of the monocotyledons, and the present 

 work was undertaken to see whether the embryo-sac structures 

 showed any deviations from the ordinary angiospermous type 

 which might be interpreted as of primitive nature. The results, 

 as we shall see, indicate that the embryo-sac in Pandanus^ at least, 

 normally differs very much from that of the typical angiosperms, 

 and that the differences indicate a less specialized condition, ap- 

 proximating the very generalized type o{ Peperomia, 



The material upon which the following account is based was col- 

 lected in Buitenzorg during my stay at the botanic gardens there 

 from March to June, 1906. The collection of Pandanaceae in the 

 Buitenzorg Gardens is without much question the richest in the 

 world, and while there I collected all of the suitable material there 



* Cannon, W. A. A morphological study of the flower and embryo of the wild 

 oat, Avenafahm L. Proc. Calif, Acad. III. i : 329-364. //. 4g-S3- I9<^- 



f Mottier, D. M. Contributions to the embryology of the Ranunculaceae. Bot. 

 Gaz. 20: 241-248, 296-304. pi. 17-20, 1895. 



J Coulter, J. M., & Chamberlain, C. J» Morphology of angiosperms, page 



I 



102. 1903. 



