168 EFFECTS OF WET SOIL. 



if its roots are immersed in water, as I ascertained some year^ 

 ago, in the Garden of the Horticultural Society, by repeated 

 experiments. Melons were planted in earth placed on a tank 

 of water, into which their roots quickly made their way ; they 

 grew in a curvilinear iron hot-house, were trained close under 

 the glass, and were consequently exposed to aU the light and 

 heat that could be obtained. They grew vigorously and pro- 

 duced their fruit, but it was not of such good quality as it would 

 have been had the supply of water to the roots been less 

 copious. In the tropics, if the quantity of rain that falls in a 

 short time is enormous, and plants are forced by it into a rapid 

 and powerful vegetation, they are at the same time acted upon 

 by free currents of warm air and a light and temperature bright 

 and high in proportion, the result of which is the most perfect 

 organization of which the plants are susceptible ; but, if the 

 same quantity of water is given to the same plants at similar 

 periods in this country, a disorganization of their tissue is the 

 result, in consequence of the absence of air, light, and heat in 

 sufficient quantity. 



The effect of contiuuing to make plants grow in a soil more 

 wet than suits them is well known to be not only a production 

 of leaves and Ul-formed shoots, instead of flowers and fruit, 

 but, if the water is in great excess, of a general yellowness of 

 appearance, owing, as some chemists think, to the destruction, 

 by the water, of a blue matter, which, by its mixture with 

 yellow, forms the ordinary verdure of vegetation. If this con- 

 dition is prolonged, the vegetable tissue enters into a state of 

 decomposition, and death ensues. In some cases the joints of 

 the stem separate, in others the plant rots off at the ground, 

 and all such results are increased iu proportion to the weakness 

 of light, and the lowness of temperature. De CandoHe con. 

 siders that the collection of stagnant water about the neck of 

 plants prevents the free access of the oxygen of the air to the 

 roots ; but the great mischief is undoubtedly produced by the 

 coldness of the soil in which water is allowed to accumU' 

 late. It is also possible that the extrication of earburetted 

 iiydrogen gas is one cause of the injury sustained by plants 

 whose roots are surrounded by stagnant water; .^ut upoa 



