PRINCIPLES OF VENTILATION. 251 



egg in four minutes, a species of chara has been found growing 

 and reproducing itself; and vegetation of an humble kind has 

 been observed in the similar boiling springs of Arabia, and the 

 Cape of Good Hope. One of the most remarkable facts on 

 record, in reference to the power of vegetation to proceed under 

 a high temperature, is related by Sir G. Staunton, in his account 

 of Lord Macartney's Embassy to China. At the island of 

 Amsterdam a spring was found, the mud of which was far hot- 

 ter than boiling water, and gave birth to a species of liverwort. 

 A large squill bulb, which it was wished to dry and preserve, 

 has been known to push up its stalk and leaves, when buried in 

 sand kept up to a temperature much exceeding that of boiling 

 water. 



Again, we have observed plants exceedingly tenacious of life 

 under the deleterious influences of carbonic acid, sulphureous, 

 chlorine and other gases. We have seen a number of different 

 kinds of plants placed in a close frame, and fumigated with sul- 

 phureous gas, the greater part of which were destroyed, though 

 a few of them were uninjured. This fact has been observed by 

 many in the fumigating of their green-houses with tobacco, when 

 some of the tender sorts would be sensibly injured by the smoke, 

 while others, though receiving a much larger portion, bore it 

 with impunity. 



It is evident, however, that though many plants will live for 

 a short time under these circumstances, a certain condition of 

 the atmosphere, as well as a given amount of light and heat, is 

 necessary to the performance of their functions, and the perfec- 

 tion of their flowers and fruit. The fact is well known, that if 

 we take a healthy plant from the light and airy green-house, and 

 place it in the room of a dwelling-house, it will become sickly, 

 and ultimately languish and die ; if it be placed in a dark, cold 

 cellar, its death will be more speedily produced. In like man- 

 ner, roses grown in a forcing-house in winter are less fragrant 

 than those grown in the warm sunshine of summer. In gen- 

 eral, plants grown in the summer months form secretions more 

 active, in every respect, than the same kind of plants grown in a 

 hot-house, under the clouded skies of winter; and even in our 

 finest forced fruits and vegetables this is perceptibly the case. 

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