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1902] ON THE DEVELOPMENT OF CERTAIN PIPERACEAE m 



chiefly, for our present purpose, in the considerably more massive 

 embryo of the former. This is however still undifferentiated 

 except for the slightly developed suspensor {fig. 2g), The pro- 

 cess of germination is also practically identical in both species, 

 except that the embryo becomes slightly more differentiated in 

 Heckeria before bursting through the endosperm {^figs, jo^ji, 



The point of chief interest in the germination of these gen- 

 era, in addition to the deferring of the formation of the organs 

 of the embryo to the time of germination, is the behavior of the 

 scanty endosperm. The endosperm of Peperomia and Hecke- 

 ria does not at any time during its development contain any 

 considerable amount of starch, though a few scattered grains 

 may appear in it during germination. These latter are perhaps 

 portions of the carbohydrate which arc temporarily fixed in solid 

 form during transmission through the endosperm. The cells of 

 this tissue in the ripe seed are pretty rich in protoplasmic con- 

 tents, with large nuclei (Johnson, 1900^, fig, ij)^ and the vac- 

 uoles are filled closely with aleurone_ grains. These facts sug- 

 gest that the chief function of the endosperm in these genera is 

 not the storage of ordinary reserve food material, as this func- 

 tion is served in these seeds by the perisperm. The later his- 

 tory of the endosperm here indicates, though absolute proof 

 must come from careful chemical work, that it really serves as a 

 digestive apparatus for breaking down and absorbing the mate- 

 rial stored in the surrounding perisperm and passing it on to the 



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embryo. If this interpretation is the correct one, then the endo- 

 sperm here fulfills the function which in many other seeds is per- 

 formed by a part of the embryo itself, as for example the scutel- 

 lum of the grasses (Haberlandt, 1896, p, 212). The aleurone 

 and denser protoplasmic contents of the endosperm cells gradu- 

 ally disappear as germination proceeds, but the cell-walls remain 

 plump and uncrushed till a comparatively late period of devel- 

 opment, except a few cells of the inner la^^er near the tips of the 

 cotyledons [figs. 36, j8). The fact that the cell-contents dis- 

 appear first from the inner layer of the endosperm might suggest 

 that this material goes directly to the embryo, but it seems quite 



