296 



EMBRYOGENY IN ANGIOSPEEMS. 



in certain cases of conjugation ; where the two cells come into contact, 

 a tube is formed between them, and the contents of the one unite 



Fig. 528. 



Fig. 529. 



Fig. 531. 



Fig. 528. Section of ovule of an Orchis (Orchis Morio), showing the poUen-tube passing 

 through the endostome, and reaching the embryo-sac in the nucleus. The closed and 

 enlarged end of the tube, t, is applied to the sac, in which a germ-vesicle had been pre- 

 viously formed. Transudation of fluids takes place, and the embryo, e, is developed at the 

 lower end of the germinal or embryonal vesicle while the upper part of the vesicle elon- 

 gates, and forms a confervoid suspensor. Fig. 529. Section of anatropal ovule, r. 

 Raphe. cA, -Chalaza. j?, Primine. s, Secundine. ac, Exostome. en, Endostome. %, 

 Nucleus, es. Embryo-sac. 'pU Pollen-tube. 5, The germ-cell which forms the emhryo. 

 Fig 530. Section of the ovule of (Enothera, showing the poUen-tube, «, with its enlarged 

 extremity applied to the end of the embryo-sac, and introverttag it slightly ; one of the 

 germinal vesicles ia the sac has been impregnated, and has divided into two parts, the 

 upper part forming a confervoid septate suspensor, s, and the lower dividtug into four parte, 

 which form a globular mass— the rudimentary embryo, surrounded hy endospermal cells, e, 

 Kg. 531. Ovule of Orchis mascula. a, Primine. &, Secundine. c, Embryo, e, Confervoid 

 filament which proceeds from the embryo towards the placenta. Fig. 532, The embryo in 

 diflferent stages of development. 1, Embryo in young state as a globular mass at the end 

 of a suspensor. 2 and 3, Embryo more advanced. 4, Embryo showing the division 

 into two cotyledons. 



