SYNTHESIS OF FATS ACCOMPANYING INTESTINAL ABSORPTION 51 
chemical reactions as well as accelerating them, and further, that the extent of action 
depends upon the power of the catalyser. 
Thus a sterile solution of starch remains indefinitely unchanged in measurable 
degree, but in presence of ptyalin or maltase is rapidly converted into dextrin and 
maltose, where the hydrolysing action ceases. On the other hand, dilute acid or 
invertin carries the process on a stage further into glucose. 
Coagulated white of egg remains tor days and weeks unchanged in presence 
of 0*2 per cent, of hydrochloric acid, or in o - 5 per cent, of sodic carbonate, but if 
pepsin or trypsin be added to these fluids respectively, it is dissolved completely in a 
few hours, and the extent and nature of the change varies with the particular enzyme 
added. Casein solution undergoes no slow soontaneous coagulation in the absence of 
its appropriate ferment, but coagulates in a few minutes when it is present. All these 
facts, and many similar ones, argue strongly for the view that an enzyme not merely 
alters the velocity of the reaction, but also that it is responsible for its inception, and 
determines its amount and character. 
Summary 
1. Absorbed fat is re-synthesized to neutral fat in the intestinal mucous 
membrane, as shown by the large percentage of neutral fat in ethereal extracts of the 
mucous membrane taken during fat absorption, and by the fact that all the fat in 
the lymph of the mesenteric lacteals during fat absorption, before the abdominal 
lymphatic glands are reached, is neutral fat. 
2. The detached cells of the pancreas, mucous membrane of intestine, and 
mesenteric lymphatic glands have a powerful action in setting fatty acid free from soap, 
and a similar action is obtained with cell-free extracts of such tissues ; but no synthesis 
of neutral fat has been obtained by the action of such cells or extracts upon solutions 
containing soap and glycerine. 
3. A comparison of results 1 and 2 leads to the conclusion that the living 
cell is capable of inducing syntheses which are not brought about by enzymes, and has 
led to a discussion of the relative properties of enzymes and cells in which the 
following conclusions are drawn : — 
(a) The type of reaction is much more complex in the case of the living cell 
than that of the enzyme. 
(b) The living cell can perform endo-thermic syntheses by causing, at the 
same time, oxidation and reduction processes in one and the same chemical substance. 
(f) Such forms of energy-transformation as occur in the cell are peculiar in 
type, and are best explained on the assumption that a form of energy, termed in this 
paper biotic energy, is developed by the living cell. 
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