276 PHYSIOLOGY. BOOK II. 



When a germinating seed has acquired the necessary 

 degree of heat and moisture, it abstracts from the air a por- 

 tion of its oxygen, and gives out an equal quantity of carbonic 

 acid gas : but, as one volume of the latter gas enuals one 

 volume of oxygen, it is evident that the seed is, in this way, 

 deprived of a part of its carbon. Some changes take place in 

 the albumen and cotyledons; and, finally, the faecula that 

 they contained is replaced by saccharine matter. In like 

 manner a flower, while expanding, robs the air of oxygen, and 

 gives out an equal volume of carbonic acid ; and a sugary 

 matter is also formed, apparently at the expense of the faecula 

 of the disk or petals. 



The quantity of oxygen converted into carbonic acid in 

 germination is, cceteris paribus, in proportion to the weight of 

 the seed ; but some seeds absorb more than others. Theodore 

 de Saussure has shown that exactly the same phenomenon 

 occurs in flowers. 



Heat is a consequence of germination ; the temperature is 

 also augmented during flowering, as has been proved by 

 Theodore de Saussure in the Arum, the gourd, the Bignonia 

 radicans, Polyanthes tuberosa, and others. 



The greater part of the saccharine matter produced during 

 germination is absorbed by the radicle, and transmitted to the 

 first bud of the young plant. Dunal is of opinion that the 

 sugar of the nectary and petals is in like manner conveyed 

 to the anthers and young ovules, and that the free liquid 

 honey which exists in such abundance in many flowers, is a 

 secretion of superabundant fluid ; it can be taken away, as is 

 well known, without injury to the flower. 



This opinion will probably be considered the better founded, 

 if it can be shown that the disengagement of caloric and de- 

 struction of oxygen are in direct relation to the developement 

 of the glandular disk, and also are most considerable at the 

 time when the functions of the anthers are most actively 

 performed. 



In no plants, perhaps, is the glandular disk more developed 

 than in Arums : and it is here that the most remarkable degree 

 of developement of caloric lias been observed. Senebier found 

 that the bulb of a thermometer, applied to the surface of the 



