424 



BOTANY. 



About this time there is inmost oases a slight differentiation 



of the inner cells, 

 foreshadowing the 

 future tissue sys- 

 tems (///. and 

 IV., Kg. 310). A 

 little later the cot- 

 yledons (one or 

 two) appear ; in 

 the Monocotyle- 

 dons, in one side of 

 the thallus - like 

 structure a depres- 

 sion forms, which 

 becomes the punc- 

 tum vegetationis of 

 the embryo, and 

 marks the limits of 

 the stem and single 

 cotyledon ; in the 

 Deootyledons two 

 cotyledons grow 

 out symmetrically 

 from the dis^al end 

 of the thallus-like 

 structure, and the 

 depression between 



Fig. 310.— Development of the embryo of Capedla them becomes the 



B«rs«-Da«ferw (highly magnified). /. ». suspenaor, or ^.,„„u,,^ ^,„„atr, 



pro-embryo of five cells, and terminate I Ik a fonr-celled }>u,tijijbaiii, vnyeia- 



embryo: 1-1, the longitudinal wail which divided the Unfn'tQ ( V TTirr 



first embryo-cell into two cells; 2-2, transverse wall '■'""«* K^^-j ^ ^S' 



which divided each cell of the two-celled embryo, mak- Q1 ^^ TVio rnnf ia 



in? it four colled. //.,«, suspensor ; A, the hypophysis, '^^^)- ■^■'^^ lOOb Ih 



the basal part of the embrj'O formed by the division of j^}^q last IDOrtion of 



the end cell of the suspensor ; the shaded portion of the ^ 



embryo is the dermatogen or primary epidermis ///., the embryo form- 



cmbryo farther advanced; the inner shaded cells con- j ., 



etiiute the plerome, between these and the dermatogen ed J its Cap (the pil- 



to the right and left are the cells of the perihlem ; the , . \ . t , 



hypophysis Is divided into two cells, A, h'. IK. srill COrhlza) IS dovelop- 



older condition. F., embryo considerably advanced'; _ji j» . i j» 



', c, cotyledons ; 8, apex of stem ; the dermatogen, peri- eci irom a layer 01 



)lem, and plerome shown as before ; jo, the rudiment- ii T.oonUir.o. fynm 



fvn as before ; w, the rudiment- „_ii ^„„„ui.m. ■P,.^^^ 

 ary root, and root-cap formed from the cell A' of ///. l^f lib I eSsUlung irom 

 and/F.-AfterH«nstein. tjjg SUCCCSSive fis- 



sion of the penultimate cell of the suspensor, the hypophy- 



