74 PRACTICAL BOTANY. 



the seed after the latter is severed from the plant, or 

 placed under favorable conditions, which previously were 

 either entirely or partially wanting. What we know 

 about the process of germination is not much, and can be 

 told in a few words. During gennination, oxygen is 

 taken up by the embryo and carbon eliminated, a portion 

 of the food, stored up within or without the cotyledons, be- 

 ing burnt by the oxygen and transformed into carbonic 

 acid and water. By this process heat is evolved, but the 

 embryo generally decreases in weight, tliougb it increases 

 in bulk, so finally, that the testa bursts, whereupon its root 

 enters the earth, the plumule developing in the opposite 

 direction into stem and branches. 



t t SORTS OF FBUIT. 



130. When a flower has its ovary, or ovaries inferior, 

 the calyx is apt to become part of the fruit, and some- 

 times forms its principal bulk, as in the Apple, Pear, etc. 

 In the strictly botanical sense, it is the papery pods, ar- 

 ranged circularly in the core, which alone compose the 

 true fruit ; the other parts of the so-called fruit are acces- 

 soiy. The rose-hip, fleshy, and usually eatable at ma- 

 turity, is a hollow, urn-shaped calyx-tube, lined with a 

 concave disk or thin expansion of the receptacle, which 

 within bears the ripened ovaries, in the shape of bony 

 nutlets, called achenia. Again, instead of the calyx, it is 

 the enlarged receptacle^ which may become part of the 

 fruit. In the Strawberry this becomes succulent and 

 sweet, while it bears the real fruit — namely, numerous, 

 hard achenia — on its surface. 



Fruits like the Bose-hip and Strawberry are called acces- 

 sory^ or anihocar pons fruits — that is, fruits, the most eon- 



