22 Professor Macaire on the 



ments. The pleasure invention gives to the mind excites at- 

 tention, and encourages the observer. But when he finds it 

 necessary, in order to arrive at some result, to repeat the same 

 thing — the same experiment, a great number of times, with- 

 out the attraction of novelty, — following scrupulously the same 

 series of operations, often long and complicated, — he then re- 

 quires to rely upon that unflinching perseverance and patience 

 which are the true test of scientific genius. All Theodore de 

 Saussure's labours are stamped with this seal. 



Without considering myself obliged to follow chronological 

 order, I shall proceed to notice such memoirs of Theodore de 

 Saussure as relate immediately to vegetable physiology ; the 

 chemical foundations of which had been laid by the beautiful 

 work of which I have just given some account. 



In a pamphlet which was reprinted in the Annates de Thy- 

 sique et de Chemie, he examined the action of the petals of 

 flowers on atmospheric air. He ascertained that the flowers 

 yield a part of their carbon to the air, where it combines with 

 the oxygen to form carbonic acid. The formation of this acid 

 gas is sufficiently necessary to them to prevent them com- 

 pleting their development in media deprived of oxygen gas. 

 Theodore de Saussure placed flowers in a receiver of atmo- 

 spheric air closed up by means of mercury, and of which they 

 occupied only the two-hundredth part, and he measured the 

 quantity of carbonic acid produced in the space of 24 hours, by 

 comparing it to the volume of the flowers taken as unity. He 

 found that the flowers absorbed more oxygen in the dark than 

 the leaves themselves. All the parts of the flower are not 

 possessed of the same intensity of action. The pistil and the 

 stamens destroy more oxygen than all the rest of the flower, 

 in the proportion, for example, in the case of Cheiranthus in- 

 canus, of 18 times their volume, instead of 11 J destroyed by 

 the entire flower ; the stamens of a male flower of a gourd, 16 

 instead of 7*6, &c. Single flowers consequently destroy more 

 oxygen than double ones, and the maximum of action takes 

 place at the time of the greatest development of the flower. 

 In dioecious plants, the male flowers consume more oxygen than 

 the female flowers. The plant which has the most decided 

 action is the Arum vulgare. Its cornet destroys five times its 



