DEVELOPMENT AT THE EXPENSE OF RESERVE-MATERIALS. 



327 



respiration, so that the dry organic substance of the young plant weighs less than 

 that of the reservoirs of reserve-material 



These observations, easily made with a little experimental adroitness, show 

 moreover not merely that the three groups of substances mentioned completely suffice 

 for the construction of the organs of the plant ; but we obtain from them another 

 important piece of information. In order to render this quite clear, we may suppose 



FIG. 22S.—Pintis rinea. I Median longitudinal section of the seed, the micropyle end being at j/ ; // commencement of germina- 

 tion, the radicle extruded ; /// end of germination after the endosperm has been absorbed (the seed lay too near the surface of the 

 soil and has therefore been carried up by the cotyledons as the stem elongated). A shows the ruptured seed-coat j; B shows the 

 endosperm e after the removal of one half of the seed-coat ; C longitudinal section of the endosperm and embryo ; D transverse section 

 of the same at the commencement of germination—«: cotyledons, -u' primary root, x the embryo-sac pushed aside by the primary root 

 (ruptured at x in Ä), h c hypocotyl, iu' lateral rootlets, r red membrane within the hard testa. 



seeds of the Pine, which contain only proteid substances and fat, or those of the 

 common garden^Bean, in which only very small quantities of fat but large masses of 

 starch are deposited in addition to the proteid substances, to be allowed to germinate, 

 until all the reserve-materials are consumed. In the seedling of the Pine we then 

 find resin-passages filled with balsam, and tannin may be detected in various cells ; 

 in that of the Bean are found numerous longitudinal rows of cells, densely filled with. 



