SCIENTIFIC MEMOIRS. 



NATURAL HISTORY. 



ARTICLE I. 



On the Circulation of Sap in Plants. 

 By Dr. HERMANN HOFFMANN. 



[From the Botanische Zeitung , vol. vi. p. 377, 1848; vol. viii. p. 17 et seq. 18. r >0.] 



, in animal physiology, many of the commonest vital phae- 

 nomena were involved in obscurity previous to Harvey's great 

 discovery of the circulation of the blood, so in the physiology of 

 plants^ not a few points are still inexplicable on account of our 

 very meagre acquaintance with the nature of the circulation of 

 the saps in vegetables. 



Every Manual of Botany gives a different view as to the 

 anatomical system in which the saps are supposed to ascend or 

 descend : many deny altogether the descent of the fluids, while 

 others are so firmly convinced of the existence of this, that they 

 have made it the basis of a peculiar kind of descending growth 

 of roots, and stated that trees grow from above downwards, in- 

 stead of upwards from below. We are likewise ignorant of the 

 relations of the milk-sap to the other juices and to crude 

 nutrient saps, so that it is still undecided whether it is to be 



SCIEN. MEM. Nat. Hist. VOL. I. PART I. 1 



