SPECIAL CASES 



597 



tip of the cotyledon of the date grows to such an extent as absorption 

 progresses that it finally almost entirely fills the cavity of the seed l . 



The extent to which the endosperm and the embryo are respectively 

 concerned in the depletion of the former can only be determined by direct 

 observation in each case, bearing in mind the fact that a very slight accu- 

 mulation of the translocatory products suffices to inhibit further mobiliza- 



FiG. 68. Seedling of Lupinus; 

 lutens. The dotted line indi- 

 cates the surface of the soil. 



FIG. 69. Seedling of 

 Mirabilis Jalapa. 



FIG. 70. Young seedling 

 of Zea Mays in median 

 longitudinal section. 



tion, which therefore soon ceases in isolated endosperm or in isolated coty- 

 ledons. Hence van Tieghem erroneously concluded that the endosperm 

 of grasses, Phoenix, &c. played an entirely passive part, whereas Hansteen 

 was able to completely or partially empty these supposed inactive storage 

 tissues by continually removing the mobilized products as fast as they 



1 For details, see Haberlandt, Physiol. Anat, 1896, p. 210; Ann. d. Jard. hot. d. Buitenzorg, 

 1893, T. xu, p. in ; Tschirch, ibid., 1891, p. 179; Hirsch, Bot. Jahresb., 1890, p. 660; Klebs, I.e., 

 p. 561 ; Ebeling, Flora, 1885, p. 191 ; Schlickum, Bibl. bot., 1896, Heft 35. 



