14>2 Circulating Sj/s/cm of Plants. 



Art. V. On the Sap-vessels, or Circulating System, of Plants. By 

 the Author of " Tl)e Domestic Gardener's Manual," C.M.H.S. 



Sir, 



I HAVE, for a considerable period, felt assured that physio- 

 logists have not as yet attained satisfactory evidence of the pre- 

 cise nature and construction of the vessels, by which the sap 

 is conveyed into, and distributed throughout, the vascular 

 system of vegetable organised beings. A\^hoever shall have 

 attentively {)erused the excellent compendium of vegetable 

 physiology, commencing p. 160. of the Pncijclopccdia of Gar- 

 dening, edition 1827, can scarcely fail to be convinced that 

 the most eminent phytologists* have employed very discord- 

 ant mechanism in their endeavours to establish, each one, his 

 own favourite theory of what has been termed the ascent, or 

 course, or circulation, of the sap. 



I am induced, at the present time, to make this communi- 

 cation, in consequence of having met with a notice, in two news- 

 papers, of a lecture recently delivered at the Medico-botanical 

 Society, by Mr. I3urnett of King's College; in which notice 

 it was stated (I quote from memory) that that gentleman 

 had produced a microscopic apparatus by which the motion 

 of the sap was rendered as apparent, without the possibility 

 of optical illusion, as the circulation of the blood in a frog's 

 foot. Struck by the force and conclusiveness of the terms in 

 which this notice was conveyed, and being desirous to ascer- 

 tain the exact truth, also to what extent the lecturer had car- 

 ried Ins observations, I addressed a letter to Mr. Ikunelt, 

 and was almost inmiediately favoured with a polite and candid 

 reply; before proceeding to state which, I am sorry to be 

 constrained to observe that the })ublic are but too often mis- 

 led by these ciu'sory notices in periodicals, which cither an- 

 nounce too much, or so mutilate and distort simple facts as 

 to produce much subse(jucnt disajipointmont. 



To tliose readers of your valuable Magazine, who arc not 

 aware of the precise nature of the discovery announced in the 

 lecture referred to, it may be gratifying to be put in posses- 

 sion of the following facts. I solicit attention to the passages 

 and words in italics, because they will be lound to refer par- 

 ticularly to the remarks with which I conclude this paper. 



In a lecture delivered in December, 1831, Mr. 13urnett 

 alluded to the experiments of Amici, Schultz, and others, by 

 which the motion of the sap of certain i)lants hail been made 

 ocularly demonstrable : a I'act which he had convinced him- 

 self was no optical illusion, by rcj)eating and varying the 



* From phyloHy a plant, and tcgo, I read, discourse of, or logot, a dis- 

 course; i. e. one who discourses of, or describes, plants. 



