328 BOTANICAL GAZETTE [November 



shape of the older embryo sac seems to indicate that their power 

 of breaking down and absorbing surrounding tissues is not as 

 great as in many other known cases. 



The embryo sac becomes filled with cellular endosperm before 

 the egg divides {^fig. 26), The very first division of the endosperm 

 nucleus has not been seen, but when four nuclei have been formed 

 these are found to be separated by cell walls, so that I believe 

 that a cell wall is formed immediately after the first and each 

 succeeding division of the endosperm nucleus, and thus the 

 endosperm is cellular from the very first. This feature of the 

 development at once recalls the case of Peperomia pellucida 

 (Johnson, 1900^), but differs strikingly from that of the 

 closely related genus Piper, as described above. Similar marked 

 differences in the mode of formation of the endosperm in closely 

 related genera have been already noted by Hofmeister (1859, 

 p. 555 et seq,\ and Hegelmaier (1885, p. 92). Evidently pecul- 

 iarities of this sort cannot be taken as adequate indications of 

 relationship, as has been recently suggested by Cook (1902) in 

 the case of Nymphaea and Sagittaria. 



The cells of the endosperm of Heckeria are at first largely 

 vacuolated and possess large nuclei. The first' cell-walls formed 

 radiate from the egg [fig. 26), but later the walls come in some- 

 what irregularly [figs. 2J, 28'). In the ripe seed there are two 

 hundred or more endosperm cells surrounding the embrj^o, in 

 from two to five layers, and occupying a broadly top-shaped 

 space at the upper end of the seed [fig, 2g). The vacuoles of 

 the endosperm cells at this time are filled closely with prote.id 

 granules, except some of the cells near the embryo, which have 

 but little contents. 



The first division of the ^gg occurs some time after the forma- 

 tion of endosperm begins, whether in consequence of fertilization 

 or not has not been made out with certainty. The direction' of 

 the first wall in the few cases seen is oblique, and the arrange- 

 ment of the cells in the many older embryos seen make it certain 

 that this is the general rule {figs. 2j, 28>^ In the ripe seed the 

 embr^'o consists of several hundreds of small elongated cells, 

 making a globular mass about 0.05""™ in diameter, undifferen- 



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