46 THOMPSON YATES AND JOHNSTON LABORATORIES REPORT 
under conditions of temperature and presence of reagents such as cannot occur in the 
living cell, and hence by methods entirely different, and probably with types of energy 
different from those utilized in the living cell. - 
If the more complex operations occuring in the living cell were due to the 
action of enzymes, there is no apparent reason why such enzymes should not be 
equally obtainable alongside the enzymes which induce the simpler chemical changes. 
No such enzymes have, however, hitherto been obtained from living cells, and hence 
the view that such processes are due to enzymes has no experimental basis, and room 
is certainly left for the alternate hypothesis that these complex syntheses, which, under 
the given conditions, are peculiar to living matter, are brought about by the presence 
of the living protoplasm, and possibly by the development of a type of energy 
peculiar to living matter, and capable of acting, in presence of the cell which plays the 
part of an energy-transformer, upon the substances present in the cell and causing 
chemical transformations which give rise to the complex syntheses under discussion. 
A second point of distinction between enzymic action and cellular activity is, that no instance 
is known in which a markedly endo-thermic reaction is capable of being induced by an 
enzyme, while there are numberless- examples of such reactions being brought about by the 
action of living cells. 
This is a characteristic difference of fundamental importance, whatever the 
explanation of it may be, and points to a much more complicated machinery for the 
induction of chemical action in the living cell than that which is present in the case 
of the enzyme. It is obvious that the energy for such endo-thermic reactions cannot 
come from the small amount of cell protoplasm, and hence it follows that the cell, in 
virtue of its structure, or of some intermediate type of energy connected with its 
structure, as a living organism, is capable of acting as an energy-transformer. The 
form of external energy so transformed may be very varied, it may be light energy, 
as in the case of the chlorophyll-containing cells of growing plants, or surplus 
chemical energy, as in the transformation of carbohydrate into fat by the connective 
tissue cell of the animal body. Even where only chemical sources of energy are 
involved, the action of the living cell is different from that of a single enzyme, in 
that energy which is obtained from the oxidation and breaking up of one portion 
of a substance can be stored in some fashion and utilized for the building up of other 
substances containing more chemical energy than that from which they were formed. 
Such a complex activity proceeding upon like substances in opposite directions at the 
same time has not been recorded in the case of an enzyme, and indicates a complexity 
of action in the case of living cells which is absent in enzymic action. Thus, when 
from a supply of carbohydrate food to a living cell, fat is formed, the process must 
consist in the oxidation of a part of the carbohydrate, and the energy so set free, 
instead of passing out of the cell as heat, must be utilized by the cell to yield the 
energy necessary for the reduction and combination of other molecules of the 
