290 General Notices. 



The action of frost upon vegetables shows itself in two ways; some plants 

 are only withered by it, but without any disruption of the membranes ; and, on 

 the return of a thaw, the leaves regain their rigidity and vigour as completely as 

 before. Other plants, from their natural or accidental succulence, delicacy of 

 membrance, and abundance of watery sap, are, by the internal crystallisation 

 of their juices, rent into shreds, and totally dismembered. Plants having a 

 resinous sap seldom suffer from frost ; because no crystallisation of such sap 

 (to hurt the tubular structure) takes place, and thus such plants escape. 



The effect of extreme heat and moisture on vegetation excites it to its 

 utmost expansion. Plants, natives of the temperate zones, if exposed to such 

 excitement for a longer time than their natural summer, become eventually 

 quite exhausted, and die in a few months. This happens to many European 

 plants when carried to India, such as the pear and apple trees ; and even the 

 grape vine lives in a very weakly condition, and is but partially fruitful, unless 

 grown on the highest hills. 



Where vegetation is deficient, there animals are mostly carnivorous ; and, 

 where vegetables abound, roots, stems, leaves, and fruit are, for the most 

 part, the food of every living creature. (Flor. Cab., vol. ii. p. 90.) 



The Effect of severe Frost on Plants. — I have been endeavouring to make 

 out something relating to the effects of frost on different kinds of vegetation, 

 but cannot satisfy myself at present on the subject. All dry substances are 

 less affected by frost than such as are of a moist nature; consequently some 

 kinds of bark, and woody fibre generally, will be less liable to injury than such 

 parts as have a watery basis. The latter must, in a great measure, come under 

 the law by which water undergoes an expansion of volume when converted 

 into ice ; and, as this expansion would take place, although confined by a 

 pressure equal to that which would burst a cannon, 1 cannot conceive how 

 the tender tissue of plants, or even woody fibre, could be preserved from being 

 totally ruptured, unless a compensation were provided for such expansion by 

 a proportionate number of air-vessels ; and, as the air is not increased, but, on 

 the contrary, goes on diminishing in volume after the watery fluid has passed 

 its minimum state of contraction, room perhaps may be, in consequence, 

 afforded for the adjoining cells to expand, as the fluid they contain is being 

 congealed and expanded. The green leaves of such plants as the holly and 

 ivy, that withstand severe frosts, are, perhaps, protected by some oleaginous 

 substance. 



I observed an instance of the destruction of the bark and cambium in a 

 China rose trained against a wall; whilst the wood admitted the free ascent of 

 sap, and young shoots, leaves, and flowers were afterwards made in tolerable 

 profusion : but the return of juices elaborated by the above-mentioned foliage 

 was completely intercepted by the disorganised state of the vessels exterior to 

 the wood ; and the consequence was, that the juices, in attempting a descent, 

 burst the bark, and formed callus-like excrescences. As soon as this was 

 observed, the stems ought to have been cut down ; for the wood drained and 

 exhausted the roots, without the latter being able to receive the usual de- 

 scending supply. In the course of the summer, about the time that the young 

 shoots ought to have been receiving a supply direct from the roots through 

 channels of fresh alburnum, they began to languish, and ultimately died. — J. 

 W. L. Nov. 17. 1838. 



Importance of Selection in setting apart Plants for 2)>'oducing Seed. — Mankind 

 seem to be just beginning to be aware of the remarkable fact, that mental 

 properties and peculiarities may be transmitted from parents to offspring, as 

 well as physical properties and peculiarities ; or, perhaps, we should rather 

 say, that mental and physical properties alike depend on organisation. It has 

 long been observed in a general way, that the offspring resemble the parent in 

 form and disposition ; but it has only in a very few cases been noticed that 

 the same thing also takes place in regard to taste. It was mentioned of the 

 man with the iron mask that he was remarkably fond of fine linen ; and as this 

 was also the case with Anne of Austria, the then dowager queen of France, 



