1818.] Death of Plants. 253 



before they are wanted, we bury them in the earth to save them 

 from the rot, and to preserve them from the frost ; and yet we 

 put in the same vegetables, almost in the same manner, to make 

 manure of them, and even expect this change to take place in 

 less time than we suffer them to remain buried for the purpose 

 of preserving them. "Now it is certain that they cannot be both 

 preserved and destroyed by the same means ; and, upon making 

 the experiment, it soon became evident to me, that we had 

 adopted a false conclusion on the subject. For some years past 

 I have been continually in want of fresh young weeds for my 

 dissections, and I found that I had only to go where the gar- 

 dener had, with great care, buried all those which he had taken 

 up in cleaning his ground ; and even after an interval of two or 

 three months, I was always sure to find a fine bed of weeds ready 

 for dissection. This happened so often that it became a constant 

 resource to me ; but it is evident that if they had made the 

 manure he expected, they could not have thrown up new shoots. 

 It is generally agreed that air, heat, and moisture, are necessary 

 to fermentation ; yet we presume that all the different stages of 

 the process will go on below the surface of the earth, and quickly 

 lead the vegetable to a state of decomposition, though it may 

 be questioned whether there be, in that situation, either air or 

 heat to assist in the operation. 



It appeared to me a subject of such great consequence to 

 solve these questions, that I determined, by accurate experi- 

 ments, to endeavour to elucidate these apparent mysteries. For 

 this purpose I formed a deep trench in which I buried all sorts 

 of weeds and plants ; so that by opening it every two or three 

 months, I might learn exactly how all plants decayed, and what 

 time is necessary for the purpose. The trench has now existed 

 for above three years : I have consequently been enabled to 

 ascertain what causes the decay of plants, and their revival, and 

 how the earth acts on them ; and 1 shall, therefore, endeavour 

 to explain what takes place while they are buried in the earth, to 

 show how veiy difficult it is to kill some plants, and to prevent 

 their resuscitation ; and I shall next show what length of time 

 the whole process occupies, particularly in woody plants : I 

 shall then revert to the best method of destroying vegetable life, 

 endeavour to determine what the life of a vegetable is, its ana- 

 logy to animal life, and the manner in which sudden death acts 

 on both ; and what visible alteration it produces in them, with 

 some other topics that naturally arise out of the subject. 



It has been the general opinion of both agriculturists and 

 gardeners, that trench ploughing, that is, cutting off the turf and 

 digging a deep ditch, and thus burying the grass, and weeds 

 taken up all around, makes in a short time a most excellent 

 manure, fit to nourish any crop. Varlo, an eminent agriculturist, 

 says, "that trench ploughing would soon form a quantity of 

 manure of a rich and good quality, and that digging two feet 

 sleep, and thus immuring all the weeds, even couch grass, 



