Academy of Sciences in Paris. 351 



first distinguished as a separate genus by M. C. A. Meyer) forms a 

 singular exception to the rest of the family of the Chenopodia in 

 having a semi-infere fruit. M. Moquin supposes the adherence of 

 the pericarpium to be owing to an intermediate discus between the 

 ovary and the calyx. The reporter, without rejecting this explana- 

 tion, remarks that the consequence deduced is not a necessary one, as 

 many plants present a large discus joined to the calyx, without having 

 the ovary otherwise than free and disengaged. 



The Sueda, the Schoberia, and the Shanginia form a little tribe 

 in the family of the Chenopodia^ the distinguishing characteristics of 

 which are a white or whitish embryo, spirally turned, usually without 

 perisperma, and always surrounded by a double integument, the ex- 

 terior of which is crustaceous. The various plants comprising this 

 tribe are described by M. Moquin with great accuracy and minute- 

 ness ; but it is obviously impossible for us to follow him into this 

 detail. The reporter observed that the work merited the full appro- 

 bation of the Academy, and urged the author to continue his re- 

 searches on the other tribes of the same family*. 



Decoloration of Leaves ; Vegetable Nutrition. On the 8th of 

 August, M. Dutrochet read an elaborate memoir on the above sub- 

 jects, of which the following is an analysis. It is well known that 

 when light is excluded from any of the vegetable kingdom the leaves 

 lose their green colour, and become of a yellowish-white. The phy- 

 sical cause of this is the loss of carbon, which, when the action of the 

 light no longer fixes it in the tissue of the plant, is poured out into 

 the atmosphere in the shape of carbonic acid, and the plant, deprived 

 of the substance to which it owes its green hue the sign of life and 

 health languishes into a morbid paleness. But the loss of carbon 

 is not the only cause of the change of colour ; it is also produced by 

 the exhaustion of the soil in which the plants are growing. Thus 

 the leaves of a plant in a garden-pot will, if not watered with manured 

 water, lose their green tint, and become white about three years after 

 they have been allowed to remain in the same mould. Three years 

 is mentioned as an average period, but the time will be greater or 

 less according to the degree of nutritive principle and to the volume 

 of the mould in the pot. An example illustrating this fact occurred 

 a short time since. A gentleman, whose house was situated on a 

 calcareous rock, dug large holes in the rock, filled them with earth, 

 and planted peach trees. These trees had every atmospheric advan- 

 tage ; the fissures of the rock allowed free passage to the rain-water ; 

 and from their full exposure to the sun and light there could be no 

 deficiency of carbonic acid ; yet, after flourishing a few years, the 

 leaves began gradually to change colour, and ultimately, when, from 



* M. Mo<juin appears to adopt the term Chenopodia as indicating the whole 

 family, and m opposition to Chenopodium, one of the genera of that family. The 

 same remark applies to the Cistinus, as opposed to the Cislus, and the Euphorbia- 

 oecs, as opposed to the Euphorbia, in the preceding report. 



