150 



FERTILIZATION. 



first expands into a proper cell, and is usually attached 

 to the wall of the sac near the micropyle. It then di- 

 vides itself transversely, becoming two cells ; tho upper 

 tlongates either with or without subdivision, forming a 

 filament (suspensor) ; the lower cell enlarges by subdi- 

 vision, first spherically, and afterwards the little mass 

 begins to take form according to the species, showing 

 cotyledons, plumule, etc., until fully developed into tho 

 embryo. 



759. Schleiden's view. Owing to the ex- 

 treme difficulty of observation in this minnto 

 field, different views of this process have been 

 advanced. That of Schleidcn should not be 

 overlooked. He maintains that the end of the 

 pollen tube actually penetrates the sac and itself 

 becomes the embryonic cell. The pollen grain is 

 in this view the primitive cell, and is itself 

 quickened into development by the contents of 



COS, Growth of the emtryo * , 



in Hippurls vulgaris. The ftrti- th G embryo Sac. 

 tizod cell has divided itsell in- Hon t? 



to several, of which c, O, con- l6 °- FERTILIZATION IN THE CONIFERS. 



etitute the suspensor attached Where no style or stigma exists, as in the Coni- 



to the apex of the sac; a , em- f ^ ]len fal]s d j reetly iato the m i cro pyle 



bryo dividing i»to 2, then into ' l J rJ 



4 cells. of the naked ovule and its tubes settle into the 



tissue of the nucleus. 



761. Chemical changes in germina- 

 tion. The ovule matures with the com- 

 pletion of the embryo, and passes into 

 the fixed state of the seed in which the 

 embryo sleeps. A store of nutritive 

 matter, starch, gluten, etc., is thought- 

 fully provided in the seed for the use of 

 the young plant in germination, until its 

 root has gained fast hold of the soil. 



762. The changes which occur in 

 the seed at the recommencement of „. 



609, Ovule of Viola tricolor, showing; 

 growth, are simply such as are requisite the process of fertilization according to 



to reduce its drv, insoluble deposits to a ?? views , of Sclll <f<^ * **j"i *> 



- ' r . *^ tube, r, raphe ; c, chalaza; 6, priuntne; 



solution which shall contain the proper a , secundinc; », nucleus; s, sac which 



materials for Cell-formation Or growth ; the tube appears to have penetrated. 



that is, gluten and other nitrogenous matters, oil, starch, etc., arc to be 

 changed to diastase, the same as yeast, and dextrine, the same as gum 

 or grape sugar. 



