The Embryo-sac of Pandanus. 
BY 
DOUGLAS HOUGHTON CAMPBELL, 
Professor of Botany in Stanford University. 
With Plates LIX and LX and two Figures in the Text 
I T is evident that the number of Angiosperms in which the embryo-sac 
shows more or less marked departures from the usual eight-nucleate 
type is larger than has been supposed. The results of recent investigations 
are sufficiently striking to warrant the hope that forms may yet be dis¬ 
covered which will throw more light upon the homologies of the structures 
in the embryo-sac of the Angiosperms, and their relation to the corre¬ 
sponding structures in the Gymnosperms and heterosporous Pteridophytes. 
In selecting forms for investigation one naturally chooses those genera 
which for other reasons are supposed to be primitive types. Among the 
Monocotyledons the Pandanaceae have been placed low down in the series, 1 
and it seemed not unlikely that Pandanus might be a satisfactory subject 
for study ; and such has proved to be the case, as it shows the least reduced 
type of female gametophyte that has yet been discovered among the 
Angiosperms. 
The Pandanaceae include the genera Pandanus and Freycinetia. They 
are confined to the Old World, being especially abundant in the Malayan 
region, where they constitute a conspicuous feature of the flora. One 
species of each occurs in Hawaii. 
During a visit to the East Indies in 1906 a large amount of material 
was collected, mostly in Java. There is a very extensive collection of 
Pandanaceae at Buitenzorg, and during my stay there from March to June 
repeated collections were made. When this material was examined, 
however, it was found to be too young to show the completed structures 
of the embryo-sac. An account of the development of the embryo-sac, as 
far as it could be followed in this material, has already been published, 2 
but the study of the further details had to be postponed until older material 
could be procured. 
The oldest stages secured from the Javanese material showed fourteen 
or sixteen nuclei in the embryo-sac, instead of the eight typical of most 
1 Pandanaceae. Engleru Prantl, Natiirliche Pflanzenfamilien, Part II. 
2 The Embryo-sac of Pandanus. Bulletin of the Torrey Botanical Club, xxxvi, 1909, 
pp. 205-20. 
[Annals of Botany, Vol. XXV. No. XCIX. July, ign.] 
