14 Investigation of the Theory 



Which of the two professors can lay just claim to priority? 

 for the theory is one and the same. But now we come to another 

 consideration. What did / write in the Domestic Gardener' s 

 Manual in 1829, which work was published complete in 1830? 

 The reader who can turn to that work, at p. 397., under the 

 head " General Remarks upon the Raspberry," will find the 

 following observations : — " Whenever raspberry plants are re- 

 moved to another situation, the old ground ought to be well 

 manured, deeply digged and turned, and then it should be placed 

 under some vegetable crop. By this mode of treatment it will 

 be brought into a condition to support raspberries again in two 

 or three years. This is a curious and interesting fact, one which 

 proves that it is not solely by exhausting the soil that certain 

 plants deteriorate, if planted on the same ground year after year ; 

 for, were this the case, manuring would renovate the ground ; 

 but it fails to do so : and thus, if peas or wheat, for example, be 

 grown repeatedly on a piece of land, the farmer may manure to 

 whatever extent he chooses, his crops will dwindle, and become 

 poorer and poorer. . . . To account for this specific poisoning of 

 the soil, we must suppose that particular plants convey into the 

 soil, through the channels of their reducent vessels, certain spe- 

 cific fluids, which, in process of time, saturate it, and thus render 

 it incapable of furnishing those plants any longer with wholesome 

 aliment: in fact, the soil becomes replete with fecal or excre- 

 mentitious matter ; and, on such, the individual plant which has 

 yielded it cannot feed. But it is not exhausted; so far from that, 

 it is, to all intents and purposes, manured for a crop of a different 

 nature : and thus, by the theory of interchange between the 

 fluids of the plant and those of the soil, we are enabled, philo- 

 sophically, to account for the benefit which is derived from a 

 change of crops." 



The foregoing remarks, whether they be correct or incorrect, 

 philosophical or unphilosophical, are tolerably pointed and 

 definite : they cannot be misunderstood ; and it will scarcely be 

 contended, that I did not pen them in the year, and in the work, 

 above mentioned. 



But Brugmans, it may be said, wrote to the same effect. I 

 deny it not : I only observe, that I know not when he did so. 

 I am ignorant of all concerning his writing, except from the few 

 lines which I have extracted from the Quarterly Journal of Agri- 

 cidture. His works are, and have been, wholly unknown to me ; 

 and you, Sir, do not appear to have referred to any of them in 

 your Encyclopedia of Plants or Hortus Britannicus. He therein 

 only is named as having given a new title to a semihardy and 

 most beautiful shrub, formerly called Datura arborea, now Brug- 

 mansm suaveolens. It is of little consequence what and when 

 he wrote, in respect to the subject under consideration ; it is 



