*^8 ROOTS ARE FORMED DURING WINTER. 



to Mr. Thoinpson's tables (page 954), that the air is very 

 generally in a state of saturation in the months of October, 

 November, December, January, and February, and that it is 

 seldom in that condition at any other season. Now, although 

 the perspiration of plants is greatly diminished by the removal 

 of the leaves, it is not destroyed, for they also absorb arid 

 perspire through their young bark; and therefore a saturated 

 atmosphere, which prevents much of the perspiratory action 

 which remains from being exercised, is a condition, even when 

 plants are leafless, riiuch too beneficial to be overlooked. Nor 

 is the action upon the perspiratory power of the stem the only 

 mode in which a saturated atmosphere is important at the time 

 of transplantation ; it exercises a directly favourable influence 

 on the formation of roots themselves. 



It is aometimes necessary to assist a tree, when it begins to grow, by 

 syringing it with a water-engine, or by binding the main branches and 

 stem with moss. The object of this is partly to stop evaporation through 

 the bark, and partly to encourage absorption by the bark. 



It is doubted, indeed, whether in the cold months of the 

 year trees make roots. Some physiologists peremptorily deny 

 the possibility of roots appearing in the absence of leaves, and 

 therefore, although they do not altogether object to the assertion 

 that roots are formed in winter or late autumn, they only admit 

 that possibility in the case of evergreens. Their theory is that 

 roots are formed by the action of leaves ; and that therefore 

 when leaves are off roots will not grow. Their theory is wrong; 

 they should use their eyes. In 1845 I examined, on the 26th 

 February, the roots of various trees, and found young ones 

 formed abundantly on Sambucus racemosa, Bibes sanguineum 

 and divaricatum, the Sycamore, Plum, Peach and Apple. Such 

 evergreens as HoUies, Garrya, Common Broom, and Portugal 

 Laurel, had also produced them in large quantity. The state- 

 ment, therefore, that roots can only be formed in the presence 

 of leaves is erroneous. 



Roots at their spongioles, or most absorbent points, are 

 extremely delicate parts, unprotected by a fully organized 

 epidermis, destined to exist in a moist medium, and capable of 

 being easily killed by exposure to dryness as well as by actual 



