many important Truths in Phytology. 103 



no heat, no exercise, that deserves the name ? What is the use 

 ■of perspiration to animal hf'e? To free the blood from its re- 

 dundant water ; to expel from the body those particles which 

 from repeated circulation" have become acrimonious. But there 

 being no circulation, there is no matter to become hurtful ; and 

 as fresh matter is hourly sent into the plant in every way, it can- 

 not want coolin;?; since tiie highest heat the plant knows is 

 •during fructiiication, which never exceeds 13° above atmospheric 

 heat at that time, and can therefore be in no danger from so 

 trifling an increase of tempsTuiure. What then is that matter 

 which philosophers collected, and called perspiption ? It is a 

 matter which, instead of proceeding from the plant, is wholly 

 drawn in from the atmosphere, and taken from the broken hairs; 

 and which may be regularly traced descending from the points 

 of the hairs, aiid thus from valve to valve, till it enters the plant. 

 Had simple nutriment alone been necessary, a naked pore would 

 have been sufficient. But to form the juices according to che- 

 mical affinity, and specijic gravity, wanted more instruments, far 

 more preparation ; and this is the reason of the very curious in- 

 struments constantly seen on the leaves, and the strange figures 

 presented to our view : few of tl^e hairs that are not double; few 

 that have not many valves, to alter the juices by degrees as they 

 meet. 



I could add many other reasons against this established idea 

 of " the perspiration of plants," did I not fear to tire my reader, 

 and did 1 not also consider that I have given amply sufficient to 

 convince all those who are not resolved not to he convinced. I 

 din sorry to say, In botany there appears such a holy horror 

 of changing established maxims, that scarcely mathematical evi- 

 dence against them will suffice. This must at once put an end to 

 every improvement in the science. And yet no one can be more 

 r.-;ai'nst admitting fads untkout strict evidence than I am. But 

 examination should always be bestowed. 



I now turn to mv second maxim, " That there is no circula- 

 tion in plants." When reading again (and with still stricter at- 

 tention) the excellent work of Sir J. E. Smith on Botany, (the 

 best compendium I know of what Phytology is at this time) 

 I, to my great surprise, discovered that Mr. Knight considered 

 both bark juice and sap as the same liquid, and forming but 

 one sort. This at once accounts for the strange mistake between 

 vs, concerning the sap, and its return through the bark. I shall 

 not stop long to consider how he can esteem as the same, two 

 liijuids so diametrically opposite in every respect, and which when 

 analysed are so essentially different: the one formed of a sort of 

 gluten and albumen extracted from the earth, and probably 

 proceeding in part from the underground vegetables^ of which 



G4 tho 



