206 Campbell: The embryo-sac of Pandanus 



the work of Johnson * and Brown f other species have been investi- 

 gated which agree in their essential structures with P. pellucida^ 

 the species in which the original discovery was made. A sixteen- 

 nucleate stage was found by Schnegg % to occur sometimes in Gii7i- 

 nera^ and Ernst § has recently shown that this is regularly the case 

 in G. viacrophylla. In the latter, however, the embryo- sac in its 

 mature condition resembles more nearly that of the typical angio- 

 sperms than does that of Peperouiia. In a preliminary announce- 

 ment Stephens |[ has stated that in several genera of the South 

 African family Penaeaceae the embryo-sac regularly contains six- 

 teen nuclei, but the details have not yet been published. Certain 

 Araceae also show certain marked deviations from the usual type, 

 but these are not constant and their meaning is still obscure.^f 

 Shattuck *'*' reports in Ubmis a)}ief'icana a condition intermediate 

 between Peperonda and the typical angiosperms. More or less 

 marked deviations from the type have also been observed In Jti- 

 glans ft and certain Liliaceae, but these are less striking than in 

 Peperomia and Gumiera, In a number of plants representing widely 

 separated families peculiarities in the antipodal cells have been ob- 

 served, which, in some cases at least, point to an increase in the 

 vegetative tissues of the gametophyte. There is often a greater 

 or less enlargement of the antipodal cells which may be accom- 

 panied by an increase in their number. This usually follows after 



"^Johnson, D. S. On the endosperm and embryo of Peperomia pelhicida. Bot. 

 Gaz. 30 : i-i\.pL I. 1900. 



. On the development of certain Piperaceae. Bot, Gaz, 34 : 321-340.//. 



9, 10. 1902, 



j- Brown, W, H. The nature of the embr>'o-sac of Peperomia. Bot. Gaz, 46 : 

 445-460. //. jz-jj. 1908. 



X Schnegg, H, BeitrSge zur Kenntniss der Gattung Gunnera. Flora 90 : l6l- 

 208. 1902. 



2 Ernst, A. Zur Phylogenie des Embryosackes der Angiospermen. Eer. Deuts, 

 Bot. Gesells. 26a: 419-438. /?/. 7. 1908. 



Stephens, E. L. A preliminary note on the embryo-sac of certain Penaeaceae. 

 Ann, Bot. 22: 329. 1908. 



^Campbell, D. H. Studies on the Araceae. The embryo-sac and the embryo 

 o{ Aglaonema and Spathicarpa. Ann. Bot. I7 : 665-687. pL ^0-32. 1903. 



. Studies on Araceae, III. Ann. Bot. 19 : 329-349. //. 14-17* 1905- 



** Shattuck, C. H. A morphological study of Ulmus americana, Bot. Gaz. 

 40: 209-223. 1905. . . 



'ft NawaSCHIN, S. Ein neues Beispiel der Chalazogamie. Bot. CentralbL 63 : 



353-357. 1895- 



