frfr- 



526 MB. II. MARSHALL "WAUD ON 



bryonic vesicle) ; it has no discernible envelope, but an especially 

 conspicuous nucleus ; and it becomes attached by the surrounding 

 protoplasm on the wall of the embryo-sac apex just below the 

 other two nuclei, which remain about the same size as at first, 

 and appear to be Strasburger's " synergidse." In most prepa- 

 rations a vacuole appears under each in the surrounding proto- 

 plasm (PI. XIX. figs. 9-11). The two " synergidse " and the 

 suspended "egg-cell " together form the " egg-apparatus" 



The nuclei at the opposite end of the embryo-sac remain un- 

 changed, apparently, and are the "antipodal cells" of authors. 

 Even in PL XIX.* fig. 9, the best instance of three of these 

 "antipodal cells" I have obtained, the third nucleus is very 

 faintly marked off from the mass of protoplasm in which all are 

 imbedded ; and consideration renders it probable that the com- 

 pletion of the division into four is not necessary* ; and it is 

 possible that in PI. XIX. figs. 7 and 8 only one antipode remains. 

 However this be, we have in Butomus an excellent type of " 

 apparatus" and " embryo-sac nucleus," with at least sometimes 

 three " antipodal cells." "What explanation can be offered for 

 these remarkable structures ? 



The general theory promulgated by Strasburger is to the 

 effect that the division into 2 x 2 x 2 of the nuclei in the embryo- 

 sac is the process of formation of a reduced prothallium by the 

 protoplasm of the embryo-sac, which, therefore, is a macrospore. 

 He further believes that the egg-cell is an archegonium reduced to 

 its oosphere, while two of the pro thai! us-cells become (syner- 

 gidae) of use in the act of fertilization by the pollen-tube f. He 

 cannot explain the fusion of the two nuclei, but believes that the 

 process has some bearing on the formation of endosperm in those 

 ovules which produce it J. The antipodal cells, according to this 

 view, are merely vegetative cells of the rudimentary prothallus. 



Vesque and "Warming, on the contrary, believe that we have in 

 the angiospermous nucellus an organ comparable to an anther in 

 some respects. Vesque describes the formation of an embryo- 

 sac mother cell as above in the main, but believes that at least 



* See in this connexion the remarks on Gymnadenia, * Quart. Journ. Micr. 

 Science/ Jan. 1880. 



t They appear to receive the pollen-tube, and act as carriers of its influence 

 to the egg. 



\ See, however, a paper by Darapski in Bot. Zeitung, August 1879. 



