10 Hints on Vegetation. 



hide, by which all the food, which the plant receives from the root, is 

 conveyed to it. However beneficial water is, all spring waters are 

 not equally so. Some waters are certainly hurtful, particularly to 

 young plants. Mineral waters, as that of Cheltenham, &c. are known, 

 by experience, to be injurious. 



4. Light and Heat. These two substances are in general so much 

 combined, that it is very difficult to distinguish the influence they re- 

 spectively have in the process of vegetation, nor is it necessary for the 

 farmer to enter into these nice distinctions. It may be sufficient to re- 

 mark, that in the opinion of Mr Knight, the more perfect plants ne- 

 ver generate an atom of true sap, (vegetable blood,) except under the 

 operation of light *, and that whenever light is wanted, little vegetable 

 blood, comparatively, is produced. Hence, in crowded crops, except 

 in very bright seasons alone, very moderate quantities of seeds are usu- 

 ally generated. 



As a proof of the importance of light to plants, it has been remark- 

 ed, that if put into a dark place, they always bend to any hole or win- 

 dow where any light is admitted. It is certain that light is neces- 

 sary, to complete the formation of oil in the seeds of oleaginous plants, 

 and that it renders fruits much sweeter, and higher flavoured than 

 otherwise they would prove. Light also greatly increases the amount 

 of saccharine matter in the sugar cane ; for the same plants, which, 

 if exposed to the light, would produce large quantities of sugar, if 

 grown in the shade, are in that respect greatly deficient. 



In regard to heat, few plants are calculated for very cold countries, 

 and those are seldom valuable ; whereas, the variety of plants pro- 

 duced in hot countries is great, and the uses to which they can be ap- 

 plied are numerous. Trees, which seem dead from the severity of the 

 cold seasons, are revived by the warmth of the spring, and strength- 

 ened by the heat of summer. They thus acquire fresh life and vi- 

 gour ; and are enabled, by the aid of light and heat, to bring their 

 blossoms, seed and fruit to maturity. 



5. Manures, or dead organized matter. It seems to be a part of 

 the beautiful economy of Nature, that nothing should have lived in vain, 

 and that the destruction of one plant, or animal, should furnish food 

 for others. Hence, however useful earth, air, water, light, and heat 

 are, to the growth of plants, it is at least questionable, whether they 

 could ever come to perfection, without the aid of matter that had been 

 formerly organized -j-. The richest soils, it is well known, are full 

 of dead animal and vegetable matter ; and there is no soil that will 

 not produce plants, if a sufficient quantity of dead animal or vegetable 

 substance's be added to it. Under this head are comprehended, all 

 those enriching and nutritious manures which are found so useful in 



* An ingenious treatise on the subject of light, written by Von Uslar, a Ger- 

 man author, translated by G. Schmeisser, in one small octavo, was printed at 

 Edinburgh, an. 1795. 



f Dr Pearson contends, that no living thing, whether plant or animal, can 

 grow, or live, without supplies of matter that has been alive, or, in other words,, 

 that living animals and vegetables, must derive their food, from dead animals 

 and dead vegetables. This doctrine is in general correct, but some recent dis- 

 coveries by Mr Knight, prove, that it does not universally hold good, some 

 plants of the Conferva family forming an exception. 



