WATER. 155 



stances disappear, and a saccharine substance is generated. 

 11 " '- is alike generated in both cases. Tlie constitutions 

 .: :. . -k and petals have been found to be similar to the 

 nourishing parts of the seed. From these facts it has been 

 concluded that the most important function of the disk and 



* lis is to aflord nourishment to the i)ollen and ovule, and 

 greatest vigor of these organs, is exhibited during the pro- 

 < of fertilization. After this effect lias been accomplish- 

 ed, these organs wither. The honey which is found in such 



-> in flowers, is the excess of the saccharine production 



: was required for the perfection of the pollen, and 



nourishment of the ovule. This excess serves for the 

 su'^port of numerous insects, and yields the store laid up by 

 the Bee, which is gathered without injury to the plant. 



Section 3. TVa/cr. 



We have already had occasion to remark on the import- 

 ^'^rG of water in vegetation, it being the only vehicle by 

 ch the plant receives its nourishment, and by its decompo- 

 sition and solidification constituting a considerable part of 

 .!)le products. It only remains for us to notice a few 

 'oints connected with the operations of this agent. This 

 it as it exists in the earth, holds in solution various earths 

 and alkalis, and vegetable and animal substances, and on this 

 account determines in a great measure the habitat of particular 

 families of plants. Those waters which contain much ve- 

 getable sulistance, nourish those vegetables whose tissues 

 abound in carbon, as our forest trees. The cruciferous plants, 

 into whose composition nitrogen enters as an element, seek 

 localities in which the waters may be more or less im- 

 pregnated with animal substances. Some families of mono- 

 cotyledons, which contain more or less of silex, flourish but 

 in those situations where the water by which they are nour- 

 ■ ' ' -N(?s through silicious soils. Leguminous plants are 

 _. partial to those waters which contain lime in great- 



er or less abundance. But the most decided influence exert- 

 ed on vegetables is that of saltwater. Many species of ve- 



* ' ' annot flourish when supplied with water which does 



-alt in solution. These plants are such as have soda 



a necessary ingredient in their composition. 



Water also varies very much the texture of plants accord- 



* *'ic quantity which enters into the tissues. Those 



-^ cs which have leaves with few pores are succulent, 



