•4.22 



FERTILIZATION AND FORMATION OF FRUIT IN PHANEROGAMS. 



early, before tlie seed enters on its I'^sting-stage. The ultimate fate of the food- 

 mntoriivl is the same in botli oases, *.«, to nourisli tlie young plant 



The relations of tlxe omhn/o to its r«sen;«-<%S8H9 are very various. la many 

 plants, e,g. Pimpernel, Wood Sonvl Snapdragon, and Strawberry-tree (^no^oUis, 

 Oxalis AoetoseUa, Antirrhinmn Diiytw. Arba.tm Unedo, <'/, figs. 817*'*>'''«'^»>».»\ 

 tlio sti-aiglit embryo lies oiuboddod in its reserve-tissue. The same relations obtain 

 in the Rue {Rata gramvloiu^, cf. tigs. 317 ^ and 317 '■■), the embryo here being slightly 

 bent; whilst in Phytolaooa dccandm (fig, ;U7 "), on the other hand,' the embryo ia 

 outside its reserve-tissue, and curved around it like a horse-shoe. In Sapindaosffl 

 and Chenopodiaceee tlie embryo is spirally twisted. In tlie Grasses it is latei'ally 

 placed to its reserve-tissue (of. vol. i. \\ 699, figs, 141 * and 141 *), and the mannor 

 in whicli it utilizes its reserve has been iil ready fully described in vol. i, p. 604 



injf, H17, HooiIh wtl.Ii II Ivtmorvt' tttimu', 



iRrUa gmvaottnt, the Intaoti toed, > LonnltudlnM teutlon ol the «i\me. •Ou'iittn Aattottlla, Intact loed. * LoogltildllMl 

 ■ootlon o{ tlie anmo. > AmmaUin jjAogniotai Intitot leod. > IiOUgttudtuftl laotton ot the iiime. ' ^cbuiui Uniito, hiMut 

 Beed. 'Longitudinal leotlon ol the lome. >,^ii(in7itiMiiii nii^iu, Int&ot leed, i° Longitudinal leotlon ot the laniii. 

 i> Longitudinal eeottou a( leed u( Phj/tolaaea (tooandra, (Atter BalUou,) 



Both the embryo and its reserve-tissue increase at the expense of the tissue 

 immediately external to the embryo-sac; and in the ripe seed very slight traces of 

 this tissue are to be found. Only in relatively few seeds is food stored in this 

 peripheral tissue (is, in the tissue of the nuoellus between the integument and 

 embryo-sac). Under these circumstances this nuoellar tissue assumes very much 

 the character of the more usual reserve-tissue (endosperm) which is formed wvthm 

 the embryo-sac. Its cells become filled with fat, starch,, and proteids, which serve 

 later on as food-material for the young plant. Reserve-tissue when stored within 

 the embryo-sac is termed endosperm,', this, which arises external to the embryo-sao 

 is, in contradistinction, termed periaperm. 



It is worthy of note that a formation of reserve-tissue does not take place in 

 ovules which are not fertilized. The act of fertilization obviously exerts an influonoo 

 not limited to the embryo. One may compare this influence to the impulse gone- 

 rated when a stone is thrown into still water. Just as waves travel in ever- 

 widening circles from the centre of disturbance, so it is with the changes in the ovulei 

 first, changes are noticeable in the egg-cell, then successively in the embryo-sao, 



