436 THIRD REPORT — 1833. 



the floscules have a tendency to take a symmetrical form on both 

 sides, so that in this case a floscule exists which is especially 

 to be regarded as impair, and which is the first or the last in 

 the spiral. This impair floscule is commonly placed either near- 

 est to the axis of the racemus (axilis), or outermost in the peri- 

 phery (perip/iericus) of the racemus. 



1 1 . The petaline floscules have a contrary progression to the 

 sepaline, so that if the odd or impair sejial is placed nearest 

 to the axis of the racemus, the odd or impair petal is placed 

 outermost in its periphery. 



\2. The situation of the impair floscule is different in dif- 

 ferent families, for example, the odd sepal, (the first or last sepal,) 

 is axilis in Labiatce, Personatce, Umbelliferce , and periphericus 

 in Leginninos^, RutacecB, &c. 



13. By the situation of the carpella two cases are to be di- 

 stinguished. 



14. In some cases the carpella are commensurable with the 

 number of floscules. They are then placed either parallel to 

 the sepals, as in the Liliacecs, Primulacece, Geraniacece, Cru~ 

 cifertB, or parallel to the petals, as in the iJ^<^aee<c, Philadelphus, 

 OnagraricB. 



15. In other families, and by far the greatest part, the car- 

 pella are two, (complete and incomplete,) and thence not com- 

 mensurable with the five divided flowers. In this case one 

 carpellum is parallel with the impair sepal, and the other 

 with the impair petal. The fruit of the Boraginece and Lahiatee 

 is to be referred to this case, two carpella taken together being 

 placed parallel to the impair sepal, and the two others parallel 

 to the impair petal, the fifth carpellum having vanished. 



Notice of Researches on the Action of Light upofi Plants. 

 By Professor Daubeny. 



The author communicated a notice of certain researches 

 which he is at present pursuing concerning the action of light 

 upon plants, and that of plants upon the atmosphere. 



He considers that he has established, by experiments on 

 plants immersed sometimes in water impregnated with carbonic 

 acid gas, and at others in atmospheric air, containing a notable 

 proportion of the same, that the action of light in promoting 

 the discharge of certain of their functions, and especially that 

 of the decomposition of carbonic acid, is dependent neither 

 upon the heating nor yet upon the chemical energy of the se- 

 veral rays, but upon their illuminating power. 



