14-2 Circulating System of Plants. 



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

 the Author of " The Domestic Gardener's Manual," C.M.H.S. 



Sh*, 

 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. Whoever shall have 

 attentively perused the excellent compendium of vegetable 

 physiology, commencing p. 160. of the Encyclopaedia 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. Burnett 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 his observations, I addressed a letter to Mr. Burnett, 

 and was almost immediately favoured with a polite and candid 

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

 constrained to observe that the public are but too often mis- 

 led by these cursory notices in periodicals, which either an- 

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

 to produce much subsequent disappointment. 



To those readers of your valuable Magazine, who are 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 found to refer par- 

 ticularly to the remarks with which I conclude this paper. 



In a lecture delivered in December, 1831, Mr. Burnett 

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

 which the motion of the sap of certain plants had been made 

 ocularly demonstrable : a fact which he had convinced him- 

 self was no optical illusion, by repeating and varying the 



* From phyton, a plant, and lego, I read, discourse of, or logos, a dis* 

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



