Life and Writings of Theodore de Saussure. 23 



volume of oxygen ; its massue destroys thirty times its vo- 

 lume, and in the part of this massue which bears the sexual 

 organs, the effect is as high as thirty-two times. 



This action is connected with another fact presented by the 

 same plant, and which has given rise to another memoir by 

 Theodore de Saussure. I allude to the heat it develops at a 

 given period of its flowering, the period which corresponds to 

 that ,of the greatest absorption of oxygen. By the use of a 

 very sensitive thermoscope, Theodore de Saussure found that 

 this heat in the Arum may rise to 7° cent, above the sur- 

 rounding temperature. He found, between 7 and 8 o'clock 

 in the morning, J degree in the male flowers of a gourd 

 {Cucurhita melopepo), still less in the female flowers. The 

 flowers of the Bignonia radicans yielded the same results. 

 For the rest, if the difficulty which accompanies experiments 

 of this kind renders the practical manifestation of this eleva- 

 tion of temperature but little apparent in flowers, it may be 

 affirmed that the first experiments of Saussure which I have 

 cited, and which prove the conversion by flowers of the oxy- 

 gen of the air into carbonic acid, afford a theoretical demon- 

 stration of it, since this conversion cannot take place but by 

 means of a true combustion. 



After having studied the action of the green parts of plants, of 

 the roots, and of the flowers, on atmospheric air, it remained for 

 Theodore de Saussure to undertake the same investigations in 

 reference to fruits. This he does in an elaborate essay inserted 

 in tlie Memoires de la Societe de Phgs, etd^Hist. Nat. of Geneva, 

 and entitled. Influence des Fruits verts sur Vair avant matu- 

 rite. In this Memoir, which contains a very great number of 

 experiments on peas, plums, wild, apples, grapes in a sour 

 state and ripe, &c., he shews that green fruits have the 

 same influence in the air, in the sun, and in darkness, as the 

 leaves. They expel oxygen from their atmosphere during the 

 night, and replace it by the carbonic acid gas which they 

 partly absorb, but in greater quantity in a receiver than in 

 the open air. In darkness, the destruction of the oxygen is 

 greater the further removed the fruits are from maturity. 



In the sun, on the contrary, they disengage Avhoily or in 

 part the oxygen of the carbonic acid gas which they have ab- 



