376 



A TEXTBOOK OF BOTANY |Ch. VIII, 



appendage which contains nutritive substances apparently 

 having a functional meaning in connection vnth dissemi- 

 nation (page 356). 



Seeds show many structural relations 

 with the ovules from whi.h thej^ develop, 

 precisel}^ as do fruits with their ovaries, 

 though it must not be inferred that all 

 such features in seeds and fruits are 

 simple persistences of ovule or ovary 

 characters. It is equally possible that 

 some have originated in seeds or fruits 

 and worked back in evolution into ovules 

 and ovaries. 



Every seed shows on its coat a tiny 



Fig. 271. — Ex-albu- 

 minous seed, of Apple ; 

 X4. 



The embryo, show- 

 ing clearly the coty- 

 ledons and hypoeotjd, 



fills completely the pit, sometimes differently colored, which 

 space inside the seed -^ -jj^g persistent though now sealed 



through which 



coats. 



IS 



MICROPYLE, or opening 

 the pollen tube entered the ovule (page 278). This of 

 course has no connection with the much larger scar, called 

 the HiLUM, left where the seed breaks away from its stalk 

 (Fig. 272). Where ovules are turned over on their elongated 

 stalks, which are growai to the coats (page 

 272), the arrangement persists, in the seeds, 

 which show a marked ridge, or raphe. The 

 position of the chalaza of the ovule often 

 is manifest in a marked chalazal anglt in 

 the seed. 



Appendages, when present, whether hairs, 

 plumes, hooks, or others, are direct out- 

 growths from the seed coat, and ha\'e 

 obvious function in connection with dis- 

 semination, as already discussed (page 356). 

 Outgrowths of the same kind occur often 

 on ovaries which contain only a single seed, 

 in which case one can tell only by dissection whether an 

 ovary wall is present or not. 



Fig. 2"-. — Seed 

 of a ]jans>' : X 5. 



Below and facing 

 to the left is the 

 hilum ; at the point 

 Unvisil>le) is the 

 micropyle : along 

 the side on the left 

 is the raphe ; and 

 at the top is the 

 chalazal angle. 



