Meyen's Report for 1839 on Physiological Botany. 31 



Euphorbia lathyris, L., which exhibits a considerable heat, 

 which vanishes completely during the night, whilst in other 

 plants traces of it remain. The hour at which plants reach 

 their maximum temperature is the same for each single plant, 

 but different for different plants ; thus for instance, Rosa ca- 

 nina at I0 h , Allium Porrum at ll h , Borago officinalis at mid- 

 day, Euphorbia lathyris at l h , Sambucus nigra at 2 h , and As- 

 paragus offic. and Lactuca sativa at 3 h . The greatest heat is 

 in the neighbourhood of the principal bud, and in woody 

 plants often only in the green extremities. Other experiments 

 confirm the fact, that plants growing in the dark lose their 

 vegetable heat, but experiments on different fungi showed 

 that these also possess a daily periodicity ; Boletus ceneus ex- 

 hibited a heat of |° C. 



Finally M. Dutrochet* has published a short note on the 

 heat of the spadix of Arum maculatum. The spadix exhibited 

 the greatest heat in the first day of blossoming, and by its in- 

 fluence the rapid opening of the spatha was produced ; on the 

 second day the maximum was not so high, and was situated 

 principally in the male flowers, by which the dispersion of the 

 pollen was effected. What Arum maculatum here exhibits on 

 the large scale is also seen in the young twigs of all other 

 plants. 



On the Odours of Plants. 



The Academy of Sciences of Brussels has given as a prize- 

 question for 1838, "The production of odours in flowers," 

 which, as it remained unanswered, was repeated for 1839. As 

 an answer to this question, M. Auguste Trinchinetti de Monga, 

 formerly Professor at the University of Pavia, has sent in a 

 memoir, which has been rewarded with the silver medal ; and 

 M. Morren has, in the name of the Academy, delivered a cir- 

 cumstantial report of this work, from which we shall here 

 select the most important parts. 



The work is divided into two sections ; the first treats of the 

 odours of flowers in general : the author speaks of the differ- 

 ence between the odours of the flowers and of the other parts 

 of plants, of the organs of flowers which exhale the odours or 

 from which they proceed, of those in which they are prepared, 

 of the chemical characters of these substances, of the manner of 

 exhalation, and lastly, of the function of odours. In the second 

 part he treats of the odours in respect to their intensity, their 

 quantity at different periods of the development of the flower, 

 and in respect to the hours at which they are perceptible ; he 

 at the same time gives methods to investigate them, and speaks 



* Comptes Rendus de 16 Dec, p. 781. 



