52 CALIFOR\'IA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



Naias, there is evident soon after fertilization a large nucleus 

 just above the antipodal cells, which undergoes no division 

 but increases very much in size. This is more variable in 

 size than \x\Naias; not infrequently it could not be detected 

 in the later stages, and in several instances it looked as if it 

 were undergoing disintegration. The thick nuclear seg- 

 ments, which are usually so conspicuous inNaias, are much 

 less so in Z annichellia , where the nucleus presents a more 

 uniformly granular appearance. Whether this nucleus is 

 in any cases the original lower polar nucleus must remain 

 for the present unanswered; but it is by no means impossi- 

 ble. The secondary endosperm nuclei, which as in Naias 

 arise entirely from the upper of the two primary endosperm 

 nuclei, are rather more conspicuous, having a very definite 

 contour and large nucleolus. They do not divide in the 

 later stages of development of the embryo-sac, but increase 

 a good deal in size. The formation of walls in the endo- 

 sperm is either rudimentary or entirely wanting. 



XI. The Fruit. 



No particular study of the development of the fruit was 

 made, but a few notes were taken which are here given. 

 The outer tissues of the nucellus remain evident at the apex 

 and base, but on the sides are almost completely destroyed 

 by the growing embryo-sac. The thin testa of the seed 

 is formed almost entirely from the outer integument. The 

 walls of the ovary become much thickened and form the firm 

 pericarp of the ripe fruit, and the style persists as a conspic- 

 uous beak at its upper end. 



SUMMARY AND CONCLUSIONS. 

 A. — Naias. 



1. A study of the development of Naias jlex His has con- 

 firmed the view as to the axial nature of the stamen and 

 ovule. 



2. The presence of tracheary tissue in stem, leaf, and 



