560 REPORT—1905. 
phagocytes has been assigned, Is this not a small and merely incidental portion 
of the duty they perform? As protoplasmic bodies they can take anything that 
may happen to reach the blood of a nature to be adapted for being linked on to 
their molecules. In this way they become the assimilative agents of the blood 
and doubtless nutrient molecules that may have escaped being dealt with else- 
where are here built into protoplasmic matter. 
The view that has been put forward assigns to the proteids of the blood the 
position of affording nutrient matter to the tissues instead of its being given by the 
transmission of the products of digestion, which, in passing through the blood- 
stream, would render the blood a chance agglomeration of small molecules that 
would suffer loss from filtration in passing through the kidney. That the proteids 
of the blood should stand in the position assigned to them is only in harmony with 
the position that proteid demonstrably holds in the case of the developing chick in 
the incubating egg. Here the only material at hand for the tissues to be formed 
from is the proteid matter within the egg. 
From the sketch that has been given of the order of events occurring in con- 
nection with the transit of food from its seat of absorption to its seat of utilisation 
the arrangement summarily expressed stands thus: Food into lymphocytes, 
lymphocytes into proteids of blood, and proteids of blood into tissue. 
The side-chain theory is looked to as affording an explanation of the mode of 
action in operation in connection with the changes that occur, Under this theory 
the basis of the protoplasmic molecule consists of a nucleus, and to this nucleus, 
side-chains, or, as they are called in immunity phraseology, receptors, are attached. 
Molecules may be linked on to a side-chain and rearrangements occur without the 
nucleus being disturbed. For linking on there must be a mutual adaptability as 
regards molecular configuration. 1f molecules are not fitted by confirmation to 
join no union can occur. If they are fitted by the exercise of affinity they are 
drawn together, and it is through what is termed the haptophore group of each 
molecule that junction is effected. A molecule having been linked on to a side- 
chain it may through the influence of the other groupings of the chain be acted 
upon and proceed by steps of degradation, regulated by the particular forces in 
operation, to utilisation with the development of energy. It is also recognised in 
the case of foodstuff molecules that they may be linked on to blood protoplasm 
and subsequently detached by tissue substance, needing nutrient material for 
growth and renovation. In this way a transport service is performed analogous 
to that by which oxygen is conveyed by hemoglobin from the lungs to the tissues, 
As with oxygen, the tissue taking on of nutrient matter will depend upon the need 
existing. In a state of tissue-repletion there will be no demand for nutrient 
matter and no taking-on capacity existing; but with the side-chain material worked 
off fresh is needed to take its place, and now it may be considered that a tissue- 
receptor affinity exists superior to that which holds the nutrient molecule in the 
transport substance, and a change of position is brought about exactly as occurs 
with the oxygen process that has been alluded to in connection with the matter. 
There is a point connected with the application of food to which I have not 
yet referred. Passage into temporary storage material is what I allude to, and fat 
and glycogen are the two principles concerned in this process. 
Storage fat may be derived from fat-supply with the food. The procedure is a 
simple one. The fat is prepared by enzyme action for absorption and is taken up 
by the epithelial cells of the villi. From these it can be traced to the centre of the 
villus, and then into the lacteal vessels, by which it is conducted to the blood. 
Reaching the blood, that which is not at once utilised is drawn into cells specially 
designed for taking and storing it. 
Fat is also derived from another kind of food-supply. In former times there 
was much dispute upon the question of whether fat could be derived from carbo- 
hydrate. The point, however, is now regarded as fully settled, and it is recognised 
that fat is readily and extensively formed from carbohydrate within the {animal 
system. In the fattening of animals the process is carried out as a branch of 
industry upon a large scale, In my ‘Physiology of the Carbohydrates, published 
in 1894, I entered into the question of the seat of the occurrence of the trans- 
