SYNTHESIS OF FATS ACCOMPANYING INTESTINAL ABSORPTION 47 
carbohydrate to form fat. • No enzyme is known which can utilize such a supply of 
energy to form fat from carbohydrate, and hence it seems probable that the 
living cell is capable of developing an intermediate form of energy, which then acts 
upon the portion of carbohydrate to be changed into fat, and yields to this the 
necessary energy for the processes of reduction and combination required for the 
production of fat. 
Such a view of a type of energy peculiar to living matter is widely different 
from the old view of a vital force or vital energy of a mystic character, and with no 
relationship to the forms of energy found in non-living matter. 
To prevent confusion, the term vital energy ought not to be used to represent 
it, the term biotic energy is here suggested, to indicate that from a definite amount of 
energy of any given type, such as solar energy or chemical energy, a type of energy 
may be produced which is capable of developing other forms of energy in the cell, 
such as mechanical or thermal energy, or the energy necessary for the production of 
endo-thermic reactions, and the evolution thereby of the complex products of organc 
synthesis manufactured by the cell. 
It cannot be too strongly urged that the production of urea, or the sugars or 
other complex organic substances by laboratory reactions, which were at one time 
believed to be capable of production only by the cell, cannot be used in any sense as 
a proof of the non-existence of such a type of energy as has been enunciated above, 
and styled biotic energy. 
Even had every individual substance formed under usual conditions in nature been 
synthesized in the chemical laboratory, no proof would thereby be given that such substances 
are formed in the living cell from the identical types of energy, or by the same intermediate 
processes, as they are formed experimentally in the laboratory. 
In proof of the above statement, it may be urged that the same chemical sub- 
stance may be formed synthetically by the use of different forms of energy ; in one 
case say by thermal energy, in another by electrical energy, and yet in another by 
radiant energy. If these are to be regarded as distinct types of energy, so also must 
the energy of the living cell, which carries out operations inexplicable by the applica- 
tion of the laws of diffusion and osmosis to the cell. 
The fact that in the living cell there exists a mechanism for energy transforma- 
tions dissimilar in structure and properties from anything found in inorganic or non- 
living nature, and producing results which cannot be imitated under similar conditions 
by any other form of energy-transformer acting only with non-biotic forms of energy, 
points strongly to the conclusion that the cell develops a type of energy peculiar to 
itself, with its own easily recognized criteria, which distinguish it from other forms of 
energy, and which is interchangeable in definite proportions with and for these other 
forms of energy. A form of energy as full of mystery as to its nature and properties 
as any of the non-biotic forms, but no more mystical than any one of them, and no 
