23 o Of Change of Species. Chap. XIV. 



w Some Plants are of an hotter Conftitution, and have 

 a quicker Digeftion, like Cormorants or Pigeons^ 

 devouring more greedily, and a greater Quantity of 

 Food, than thofe of a colder Temperature, of equal 

 Bulk, whole Sap, having a more languid Motion, in 

 proportion to the lefs Degree of Heat in it, fends off 

 fewer Recrements ; and therefore a lefs Supply of Food 

 is required in their room. This may make fome Differ- 

 ence in the one's fucceeding the other ^ becaufe the 

 hot-conftitution'd leaves not enough for its own 

 Species to fucceed again, but leaves enough for a 

 Species of a colder Conftitution to fucceed it. 

 i But the Third and chiefeft Caufe of the Benefit of 

 changing Sorts is Quantity of Tillage, in proportion 

 to which the Food will be produced. 



The true Caufe why Wheat is not (efpecially on 

 any ftrong Soil) to be fown immediately after Wheat, 

 is, That the firft Wheat (lauding almofl a Year on 

 the Ground, by which it mud grow harder -, and' 

 Wheat Seed-time being foon after Harveft in Eng- 

 land, there is not Space of Time to till the Land fo 

 much as a fecond Crop of Wheat requires. 



Tho' fometimes in poorer Land, that is lighter, 

 Wheat has fucceeded Wheat with tolerable Succefs; 

 when I have feen, on very rich ftrong Land, the firft 

 Crop loft by being much too big, and one following 

 it immediately, quite loft by the Pcornefs of it, and 

 not worth cutting. 



This was enough to fitisfy, that the Tillage which 

 was fo much eafier performed in lefs Time, fufficed 

 for the light Land, but not for the ftrong : and, if 

 the ftrong Land could have been brought into as 

 good Tilth as the light (like as in the new Hufbandry 

 it may), it would have produced a much better fecond 

 Crop than the light Land did. 



From ail that has been (aid, thefe may be laid 

 down as Maxims -, viz. That the fame Quantity of 



Tillage 



