TEMPERATURE. 
83 
accompanied with moisture, is the formation of extra foliation in* 
the plants, long-jointed weak growths ensue, a yellow sickly 
appearance is assumed from the plant’s inability to decompose 
its food, and the production of flowers is prevented. A high 
temperature devoid of moisture affects vegetation in a still more 
ruinous manner when persisted in for any length of time ; from 
the rapid abstraction of the fluids by perspiration, which the roots 
are unable to make good, the epidermis is left in the position of 
a kettle on the fire with no water in it, and must consequently 
“burn,” a term but too well known in the garden. These ex¬ 
tremes are then to be avoided as alike dangerous, yet an 
occasional moderate approach to either may in certain cases be 
found highly beneficial. It will be seen the effects of a high moist 
temperature are exhibited in the increase of tissue, or a disposition 
to grow, and so long as this course is modulated to the natural 
habits and power of the plant, it may be highly beneficial; 
on the other hand, an elevated atmosphere devoid of moisture, 
restrains the action of the plant to the elaboration of its secre¬ 
tions, as is seen by its hardened tissue and the gradual suspension 
of its growth ; under a favorable regulation it may be made the 
most efficient agent to the inducement of a flowering state in all 
vegetation, and thus by judicious management the very causes, 
which in excess are so highly injurious, may be made conducive 
to the happiest results. It is a singular fact that the effects of 
cold resemble those already described as resulting from heat, and 
with the exception that the tissue is not elongated in an unnaturally 
low temperature, the analogy holds good through each gradation. 
The action of cold winds is equally enervating with that of a 
hot sun, the juices of the plant are extracted in either case by 
evaporation, and if continued for any length of time, must prove 
alike the cause of death. Frost is more closely analogous to an 
excessively high and moist temperature, as in each case the injury, 
though arising from opposite causes, is inflicted by the disrup¬ 
tion of the vessels of the plant, and the consequent derangement 
of its vital action ; the former by congealing the fluids arrests 
their motion through the system of the plant, and their expansion 
by bursting or unnaturally distending the sides of the cells, im¬ 
pairs the excitability in exactly the same manner that the plethoric 
induction arisiug from the latter has been observed to do. 
