TO THE READER. 



The present Treatise ' On thePhenome non of Rejuvenes- 

 cence in Nature, especially in the Life and Development 

 of Plants,' was issued to a small circle in May of last 

 year, from the High School of Freibuirg, in the Breisgau, 

 to which the Author at that time belonged, and for which 

 it was especially composed, as a Prorectorate Address; 

 its publication to wider circles of the Scientific world 

 has been delayed by many circumstances, partly connected 

 with the change of residence of the Author, through his 

 call to the High_School of Giessen^ partly in consequence 

 of the events which afflicted the country mth dissensions, 

 and obstructed the calm progress of scientific undertak- 

 ings. Nevertheless, the Author hopes that the substance 

 of the Essay, which contains an attempt to combine the 

 special branches of Botanical research more intimately 

 together and with the entire body of Science, by means 

 of certain connecting ideas, and to grasp and trace out 

 the old questions under a new point of view, has not 

 meanwhile grown out of date, so that he may venture to 

 comply with friendly requisitions from many quarters, and 



