SPERMATOPIIYTES : ANGIOSPERMS 



217 



cotyledons, and the seed coat containing the cotyledons 

 remains like a lateral appendage upon the straightened axis. 



It is also to be observed in 

 many cases that the young root 

 system, after gripping the soil, 

 contracts, drawing the young 

 plant deeper into the ground. 



118. Summary from Anglo- 

 sperms. — At the beginning of this 

 chapter (§ 107) the characters of 

 the Gymnosperms were summar- 

 ized which distinguished them 

 from Angiosperms, whose con- 

 trasting characters may be stated 

 as follows : 



(1) The microspore (pollen- 

 grain), chiefly by insect pollina- 

 tion, is brought into contact with 

 the stigma, which is a receptive 

 region on the surface of the car- 

 pel, and there develops the pollen- 

 tnbe, which penetrates the style 

 tu reach the ovary cavity w^hich 

 contains the ovules (megasporan- 

 gia). The impossibility of con- 

 tact between pollen and ovule im- 

 plies inclosed ovules and hence 

 seeds, and therefore the name 

 " Angiosperm." 



(2) The female gametophyte 

 at the time of fertilization con- 

 sists of only a few free nuclei and 

 cells, usually seven in number. 



(3) The female gametophyte produces no arcliegonia, 

 but a single naked egg. 



Fig. 194. Seedling of hornbeam 

 (C'arpinus), showing primary 

 root {hiv} bearing rootlets {^w) 

 upon wliich are numerous 

 root hairs (/•), hypocotyl (A), 

 cotyledons (c), young stem 

 ((?), and first (l) and second 

 (/') true leaves.— After Scuim- 



PEU. 



") 



