BOTANICAL INFORMATION. 187 
globe that on account of their cold would be uninhabitable ; which allows 
the development of aquatic vegetables in frozen water ; which defends 
trees against winter, and which, in tropical regions, causes vegetables 
to withstand a temperature often too high for their organization. The 
observations upon the elevated temperature in the flowers of Aroideous 
plants in general, have shown that this phenomenon takes place in a 
high degree, and originates in a sort of combustion, that is to say, an 
absorption of oxygen and emission of carbonic acid. 
Very recently a high degree of temperature has been observed in a 
plant belonging to a family in which that phenomenon has not been 
noticed before. Mr. Teysman, chief gardener at Burtenzorg (in Java) 
in 1845, has informed me that he has observed an elevated tempera- 
ture, and at the same time a very strong smell, in the male cone of 
Cycas circinalis. I received from him, in October 1849 and Novem- 
ber 1850, seven series of observations, made in the aforesaid garden, - 
upon male flowers of this plant. What is most remarkable in these 
observations is connected with the following facts. The elevation of 
the temperature always takes place between 6—10 o'clock in the even- 
ing. Messrs. Bory (at the Isle-of France) and Hasscarl (at Java) have 
observed the maximum at 6 o'clock in the morning. De Saussure 
observed it in the 4rwm Italicum between 4-7 in the evening; and the 
Colocasia odora in the gardens of Paris, Amsterdam, and Leyden has 
always attained its maximum at noon. This periodical production of 
heat, differing in different climates and in flowers of different families, 
has not yet been accounted for. It appears from the inspection of the 
tables of several hundreds of observations, that the maximum has 
varied between 9-14? C., and the difference has been 3:75—4:509, 
It is acknowledged that in general the coloured parts among the 
appendieular organs in vegetables have an absorption. and ex 
contrary to those of green parts. The oxygen is absorbed, carbo 
acid is exhaled. Both take place in organs where the elevated tem- 
perature is shown in a high degree. It is proved that this pheno- 
menon is constantly preceded and accompanied by rapid growth in the 
flower. Nothing prevents us from admitting that the same action 
actually takes place in the male cone of Cycas, where the rapid deve- 
lopment of pollen, or the formation of cells which compose it, should 
surpass all that has been observed in this respeet in the vegetable 
kingdom. 
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