140 On Changes of Temperature in Plants. 



something so surprising. The recent investigations of the most 

 celebrated geologists, tend to prove that the phenomena of vol- 

 canoes are intimately connected with the state of fusion and in- 

 candescence of the internal nucleus of the globe ; nor does their 

 explanation present any difficulties. The hypothesis of central 

 heat, at first so keenly contested by the greater number of na- 

 turalists, now rests on so great a number of facts, collect- 

 ed by men entertaining such different opinions, in countries 

 so remote from each other, and under such diversified circum- 

 stances, that it is very difficult to combat it with success. 

 Sir H. Davy himself, at the end of his memoir, admits that this 

 theory possesses much probability. Such is almost always the 

 fate of great truths, moral as well as natural. After exciting the 

 contempt, frequently the sarcasms and persecutions, of party- 

 spirit (for the sciences, unfortunately, are not free of it), they 

 always end, after a greater or less period, with triumphing 

 even over the most exaggerated ; and often he whom it has been 

 found most difficult to convince, becomes one of the most ardent 

 enthusiasts in the cause which he formerly repelled with so much 

 obstinacy *. 



On Changes of Temperature In Plants. 



In a thesis sustained at the University of Tubingen, Dr W. 

 Neuffer has presented the results of a number of interesting 

 researches into the changes of temperature which plants undergo. 

 In a thesis presented by M. Haider in 1826, on the same sub- 

 ject, the author asserted that trees are in winter at a lower tem- 

 perature than the freezing point, and even pass to the state of 

 congelation, without injury to their life. The winter of 1827 

 and 1828 being very severe, the necessary observations were 

 made at Tubingen for confirming those of M. Haider. The 

 temperature of a poplar was observed during the whole of the 

 year 1828, and the results of this examination differ httle from 

 those obtained in the Botanic Garden of Geneva, and published 

 in the first volume of the Bibliotheque Britannique. The tem- 

 perature of the air and that of the tree were about equal in Fe- 



• In the former Number of the Journal, we gave Sir H. Davy's own ac- 

 count of his desertion of the metalloidal theory of volcanoes, and his tracing 

 volcanoes to the action of the central heat. — Ed. 



