298 ANNUAL RECORD OE SCIENCE AND INDUSTRY. 



the mean temperature in each case is about the same. 19(7, 

 xx\i.,J((h/ 1, 209. 







INFLUENCE OF HEAT OF SOIL ON GROWTH OF PLANTS. 



The result of an investigation by Bialoblocki, in regard to 

 the influence of the warmth of soil upon the development of 

 certain cultivated plants, is summed up by him in the follow- 

 ing words : The influence of warmth of the soil is made man- 

 ifest in two directions : in the shortening or lengthening of 

 the period of vegetation, and in affecting the external form 

 of the plant, the acceleration of growth of vegetation occur- 

 ring principally in the earlier periods. With an ascending 

 temperature of the soil, vegetation is forwarded up to a cer- 

 tain point. From the moment, however, when this point is 

 reached, an increase of temperature in the soil actually retards 

 growth. The maximum point of favorable temperature of 

 the soil varies for different plants, but the maintenance of a 

 constant temperature has for its result a more vigorous growth 

 of the plant experimented on. The extreme limit of a con- 

 stant temperature of the soil at which a growth of the roots 

 can still take place we may assume to be below, but very 

 near 104 Fahr. A ground temperature of 50 Fahr. barely 

 allows plants to fulfill completely all their functions of life 

 and conditions of development. An increased ground tem- 

 perature has no special influence upon the absorption of nu- 

 tritious matter through the roots, and the accelerated growth 

 resulting from an increase of heat is usually accompanied by 

 a greater percentage of water in the plant. 18(7, xxxi., Au- 

 gust 2, 486. 



GROWTH OF PLANTS IN AQUEOUS SOLUTIONS. 



Experiments have been prosecutect of late by German phys- 

 iologists in regard to the cultivation of plants in aqueous so- 

 lutions of different substances without the addition of any 

 earth, and, as the general result, we are informed that a 

 plant w r ill grow, bloom, and ripen fruit without being insert- 

 ed in soil of any kind, but simply in a liquid which contains 

 eight different substances, namely, potash, lime, magnesia, 

 iron, sulphuric acid, phosphoric acid, chlorine, and nitric acid, 

 the nitric acid being capable of being replaced by ammonia 

 or hippuric acid, uric acid, etc. It is furthermore stated that 



