8 EXPERIMENTS ON THE HEAT OF LIVING PLANTS. 



He took nine ounces of the bulbulli which grow on the umbels of the 

 Allium sativum, at the moment when the leafits were near developing. 

 He examined them during ten days, repeating his observations three 

 times a day : the maximum of caloric observed was from 2 to 3°. Nearly 

 the same results were obtained by pounds of bulbulli of the Lilium 

 tigrinum, and by potatoes the size of a hazel nut. 



C. Experiments- made on plants already developed, and in full vege- 

 tation. — That which especially prevents the discovery by these experi- 

 ments of results, analogous to those furnished by germination, is the 

 considerable exhalation of vegetables, by which certain plants lose in 

 one day nearly half the weight of their leaves. After having taken the 

 precautions necessary for making decisive observations, the author was 

 convinced that the young oat plants were of a higher temperature by 

 two or three degrees than the surrounding air. The maize and the 

 Cyperus esculentus showed an increase only of from 1 to Similar 

 results were obtained from the following plants : — Hyoscyamus niger, 

 Sedum acre, Pinus abies, Eupatorium cannabinum, Solidago arguta, 

 and the fruits of the Mespilus cotoneaster. The Spergula arvensis had 

 exhibited during germination a higher temperature than the other 

 plants ; and plants in full vigour gave the same results. In a few 

 hours the thermometer rose from 16° to 26° : this result may partly 

 proceed from the fact that plants contribute to the restoration of each 

 other, and by that means prevent the escape of caloric. 'Peas, observed 

 at. different stages of growth, constantly presented a higher tempe- 

 rature. 



At the conclusion of his memoir, M. Goeppert again speaks of caloric 

 being developed by the Aro'idcoc. The Arum dracunculus exhibits a 

 considerable increase of caloric ; the anthers especially evince its escape : 

 when cut, they still preserve during twenty-four hours a higher tem- 

 perature than the atmosphere. The highest degree of heat observed in 

 the flowers of this plant is from 27 p to a temperature of 13 Q . The ob- 

 servations made to discover the development of caloric in the flowers 

 of the Cactus and the Malvas have hitherto produced no results : the 

 author, however, does not despair of obtaining them in the course of 

 time. 



[ Our younger readers may be told that the evolution of heat both in animals and 

 plants, is, so far as we know, the result of the combination of various gases, the 

 heat being, as it is conceived, forced out from between their particles, when these 

 particles are pressed closer together Editor.] 



