Campbell: The embryo-sac of Pandanus 213 



show a distinct reticulum, while in the younger sac the contents 

 of the nucleus appear more compact and uniformly granular. 

 The nucleolus also increases much in size and becomes very con- 

 spicuous. In P. Artocarpus the increase in size is more marked 

 in the chalazal nuclei than in the micropylar ones, which are 

 noticeably smaller. In the most advanced stages the arrangement 

 of the nuclei is very similar to that in Peperoviia Jdspidula described 

 by Johnson, except that there are fourteen instead of twelve 

 chalazal nuclei in the latter, and these ultimately fuse into one 

 enormous endosperm nucleus. No indications of any nuclear 

 fusions were met with in any of the embryo-sacs of Pandanus, and 

 the final history of these large chalazal nuclei must for the present 

 remain undecided. 



Paitdantis odoratissimus was also examined for comparison 

 with P. Artocarpus^ from which it was found to differ only in some 

 minor particulars. This species has very large fruits with the 

 carpels united into groups, forming more or less complete com- 

 pound pistils, but the union of the carpels is a very loose one. 

 The upper part of the carpels soon becomes very hard and woody, 

 but the base remains succulent for some time and is easily sec- 

 tioned. The inflorescences from which the preparations were 

 made were about 6 centimeters in diameter, and it was supposed 

 that these carpels had already been fertilized. It was therefore 

 hoped that the later stages of the sac would be obtained, but ex- 

 amination showed that in spite of the large size of the carpels, 

 which were nearly 2 centimeters in length, the ovules were little 

 further advanced and not noticeably larger than those in the 

 apparently much younger and smaller flowers of P. Artocarpus. 

 An examination of the stigma showed the presence of pollen- 

 spores, some of which were still ungerminated, while others had 

 emitted the pollen-tubes. None of the ovules that were examined, 

 however, showed the presence of the pollen-tube, and the ques- 

 tion must still remain open whether the sac undergoes any further 

 changes before the actual fertilization occurs. In P. odoratissimus 

 the two micropylar nuclei are quite as large as those of the chal- 

 azal region (fig. 21), and the largest sac found in this species was 

 slightly larger than that of apparently the same age in P. Arto- 

 carpus. In P. odoratissimus a few nuclei were seen which con- 



