150 



FERTILIZATION. 



608, Growth of the emtryo 



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 ; the upper 

 elongates 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 the 

 embryo. 



759. SCHLEIDEN'S VIEW. Owing to the ex- 

 treme difficulty of observation in this minute 

 field, different views of this process have been 

 advanced. That of Schleiden 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 



inHippurisvuIgaris.Theffcrti- tne embryo Sac. 



lized cell has divided itsell in- Hnr\ T- 



to several, of which c, 6, con- 760 ' FERTILIZATION IN THE CONIFERS. 



stitute the suspemor attached Where no style or stigma exists, as in the Coni- 



4 ceils. 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 4 ., 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 



Pollen ; t, 

 , primine ; 



proper a , secundine ; 71, nucleus ; s, sac which 

 materials for cell-formation or growth ; tlie tube a PP e ars to have penetrated. 



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

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

 or grape sugar. 



to reduce its dry, insoluble deposits to a th views , of Schlei(1 ^. p, 



, . i- 1 -, tube, r, raphe; c, chalaza; 



Solution Which shall contain the 



