ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 117 
Eggs are, of course, good binders, since egg-albumen (with a gold 
value of 0°15 to 0:25) is a strongly-protecting colloid. 
In the literature concerning ice-cream one finds the term ‘filler’ 
applied to these added colloids, but the term ‘ binder’ is probably 
to be preferred. 
This problem once again opens up the question as to the ultimate 
action of a protecting colloid ; the usually-accapted idea is that the 
colloid forms a membrane around the particles of the suspension 
material and so prevents the coalescence. This is Bechold’s adsorp- 
tion view. (Of. Zeit. phys. Chem. 48, 385 (1904) ). 
[The question of ‘protection’ is considered in detail in W. D. 
Bancroft’s report upon Peptization and Precipitation, Cf. p. 2. 
W. C. M’C.L.] 
COLLOID CHEMISTRY IN PHYSIOLOGY. 
By Professor W. M. BAyuiss, F.R.S., University College, London. 
Introductory. 
Since all physiological processes occur in complex heterogeneous 
systems, both coarsely heterogeneous and colloidal, it is clear that a 
complete discussion of the subject would include practically the 
whole of the science. Even in the functions of the central nervous 
system, which might seem most distant from colloidal chemistry, we 
have to take account of the properties of the membranes which inter- 
vene between the component elements, and certain observations made 
on these elements themselves will be referred to incidentally in the 
following pages. There are, however, some regions in which col- 
loidal properties play a more obvious and better known part. These 
concern especially the nature and properties of protoplasm itself, 
including the membrane which surrounds it, and the relationship 
of their constituents to electrolytes. Another problem that will 
appropriately be considered is the nature and functions of enzymes, 
which regulate the chemical reactions of the living organism. And 
finally, the remarkable properties of haemoglobin in relation to the 
transport of gases require brief consideration. 
BIBLIOGRAPHY. 
Bayuiss, W. M. (1918), ‘Principles of General Physiology.’ Second Edition. 
Chapters I, III, IV, Vand X. (Longmans and Co.) 
MatueEws, A. P. (1916), ‘Physiological Chemistry ’—especially pp. 190 to 265, 
(Bailliére and Co.) 
McCuirenpon, J. F. (1917), ‘Physical Chemistry of Vital Phenomena,’ pp. 240. 
(Princeton University Press.) 
I. Protoplasm and Cell Contents. 
When a simple unicellular organism, such as amoeba, which 
consists of so-called “naked”. protoplasm, is examined under the 
microscope, it is seen to contain a variety of granules and other 
inclusions of comparatively large size. These lie in a clear, appar- 
ently structureless, substance which is in contact with the water in 
which the animal lives. For this latter reason, the protoplasm is 
said to be naked, in contradistinction to vegetable cells, such as 
algae, which are clothed with a cellulose coat. 
