2 ] [Book VIII. 



C H A P. II. 



FLUIDS OF VEGETABLES, 



f 'be. S/tcctts Ccmmunis or Sap. Vcffels for the Circulation of the 

 &aj>- Succus Proprlm ; its VeJTds and 'Ccurfe. Bonnet's Experi- 

 ments on the Nourifonent of Plants. Dr. Hole's Experiments on Fruit 

 Trees. Bonnet' 's on Fltnveri, &c. 



THE fluids or juices of vegetables, fays Dr. Bell, 

 ,are of two kinds. < The one is of the fame nature 

 in all the variety of vegetables : die other varies ac- 

 cording to the different plants in which it exifts. The 

 former, which is called the fuccus commitms, when 

 collected early in the fpring, from an incifion made in 

 the birch or vine, differs little from common water*. 

 The latter, which is named thefuccttspfoprius-, pofieffes 

 various properties in various plants, and gives to 

 each its fenfible Qualities. Theje two juices never 

 mingle with each other in the tree, and the latter is 

 found in the vafa frofiria only. 



< It is not yet ' alcertained, whether :he juices of 

 plants are tranfmitted through vefiels, or cellular fub- 

 fiance. Each fide of the queftion has had its advo- 

 cates, who have fupported their refpettive opinions 

 with probable arguments : but it is to, be regretted, 



* It has, however, been al'edged to contain a faccharine matter 

 in fome trees, as in the f-j^ar maple, &c. It has likevvife been fup- 

 pofed to contain an acid. Bat, in various experiments which Dr. Belt 

 made on it, he found nothing in it of either kind ; and therefore, 

 where fuch appearances have taken place, he fuppofed them to 

 ar,ife from an adventuious mixture of the fap, and the fuccus 



