BOTANY. 315 



plants is greater than in the air, which is, doubtless, explained by sup- 

 posing that the ozone disengaged during the day continues to surround 

 the plants during the night when the weather is calm. 4. Plants in 

 the country give off more ozone than those in the town during the 

 day, probably due to vegetative life being more active, the former 

 also reducing more carbonic acid. 5. Hence we may infer that the 

 air of the country and that of habitations surrounded by vast gardens, 

 forests, etc., is more vivifying than that of towns. 6. In the midst of 

 towns and a concentrated population, the ozone of the air at night is 

 more considerable than the ozone of the air by day. If we go away a 

 little from this concentration of men, and enter into that of plants, the 

 excess of the ozone of the night above that of the day diminishes ; and 

 if we advance further into the country, where plants are more numer- 

 ous than men, the ozone of the day becomes more considerable than 

 that of the night. 7. The interior of the corollas gives off no ozonized 

 oxygen. 8. In dwelling-rooms oxygen does not generally exist in the 

 ozonized state." 



PHOSPHORUS IN VEGETATION. 



M. Benjamin Corenwinder has lately contributed a voluminous paper 

 to the French Academy describing experiments which shed much light 

 on the manner in which phosphorus exerts such a beneficial effect on 

 vegetation. The results that he arrives at are. 1. That plants when 

 young always yield ashes rich in phosphoric acid, but that after the 

 plant has produced its seed or fruit, the stem or leaves contain very- 

 little of that principle. 2. That phosphoric acid exists in plants in 

 close combination with nitrogenous matter. 3. That the organs of 

 plants, not containing any nitrogen, and ill-adapted for food, contain 

 no phosphates. 4. That the exudations of plants, such as manna and 

 gum-arabic, do not generally contain phosphoric acid. 5. That if the 

 skeleton of a young plant be separated from the pulpy matter, all the 

 phosphoric acid remains in the latter ; so that, unlike the skeletons of 

 animals, those of plants do not owe their solidity to any phosphates. 

 6. That marine plants, growing on rocks, contain a large quantity of 

 phosphates, as also the pollen of flowers, and the spores of cryptoga- 

 mous plants. 



