Reviews. — Lindlty^s Theory of HorlicuUure. 27 



have seen for many previous years. This fact completely 

 overthrew the last favorite theory of the cause of blighted 

 fruits; viz. that the trees lacked moisture, and that frequent 

 waterings, or keeping the ground wet about the roots, would 

 be attended wiih favorable results. Another theory main- 

 tained that the present race of St. Michael trees in this vicini- 

 ty, were from deteriorated scions of deteriorated trees, and 

 that by procuring those from trees yet healthy, the fruit would 

 regain its reputation. tSo far as our own observations ex- 

 tended, the crop of St. Michael pears of this year, set at defi- 

 ance both of these theories. 'Tis well, however, to suggest 

 and to adopt, hoping for some future important end. Pro- 

 fessor Lindley, in his chapter on bottom heat, offers some sug- 

 gestions. 



It may hence be consitlerefl an axiom in horticulture, that all 

 plants require the soil, as well as the atmosphere, in which they 

 grow, to correspond in temperature with that of the countries of 

 wiiich they are natives. It has also been already shown, that the 

 mean temperature of the soil should be a degree or two above that 

 of the atmosphere (119.) 



This explains why it is that hardy trees, over whose roots earth 

 has been heaped or paving laid, are found to sutler so much, or even 

 to die; in such cases, the earth in which the roots are growing ia 

 constantly inuch colder than the atmosphere, instead of warmer. 

 We have here, also, the cause of the common circumstance of 

 vines that are forced early not setting their fruit well, when their 

 roots are ittthe external border and unprotected by artificial means; 

 and to the same cause is often to be ascribed the shrivelling of gra[)es, 

 which, as we all know, tnost commonly happens to vines whose 

 roots are in a cold and unsunned bonier. 



Mr. ileid of Balcarras has, indeed, shown that one of the causes 

 of canker and immature fruit even in orchards is the coldness of the 

 soil. He found that, in a cankered orchard, the roots of the trees 

 had entered the earth to the depth of three feet; and ho also ascer- 

 tained that, during the summer months, the average heat of the soil, 

 at six inches below the surface, was 61^; at nine inches, 57'; at 18 

 inches, 50^; and at three feet, 44^. He took measures to confine the 

 roots to the soil near the surface, and the consequence was, the dis- 

 appearance of canker, and ripening of the fruit. (Memoirs of Cale- 

 donian Horl. Soc. vi. part 2; and Gardener's Magazine, vii. 55.) 



We indeed remember seeing a year since, some dwarf 

 trees of the St. Michael, full of fair and large fruit, transplanted 

 a (ew months before; perchance the partial injury done to the 

 roots, and the fact that they were near to the surface of the 

 soil, were promotive of the crop. 



In forcing the grape and other fruits, and in the process of 



