AN-£> INSENSIBLE PF.RSPlRATIONt CJ 



cd by the warm clays of autamn, when tlie 

 nights are cold, than in much hotter weather 

 in summer, and this is surely from the same 

 t:ause as the autumnal flowing of the vegetable 

 sap. 



The sap, or lymph, of mbst plants when 

 Collectt;d in the spring as above mentioned, 

 appears to the sight and taste little elsti than 

 water, but it jK)on undergoes fermentation 

 and putrefaction. Even that of the Vine is 

 scarcely acid, though it can hardly be ob- 

 tained without some of the secreted juices, 

 which in that plant are extremely acid and 

 astringent. The sap of the Sugar Maple^ 

 Acer saccharinum^ has no taste, though ac* 

 cording to Du Hamel every 200lb. of it will 

 afford lOlb. of sugar. Probably, as he re- 

 marks, it is not collected without an adraix^ 

 ture of secreted fluids* 



As soon as the leaves expand, insensible 

 perspiration takes place very copiously, chief- 

 ly from those organs, but also in some degree 

 from the bark of the young stem or branches. 

 The liquor perspired becomes sensible to us 

 by being collected from a branch introduced 

 into any sufiiciently capacious glass vessel, 



