Incipient Vitality . 23 
that which takes place in the test-tube take place also in the cell. 
It is very interesting to note that the desired rapprochement 
between the test-tube and the cell is not all the work of the biologist 
who craves for it, but is largely the work of the less emotional 
chemist. With the growth of the science of Physical Chemistry a 
change has come over the chemist’s point of view bringing it much 
more that is everywhere realised into line with that of the biologist. 
Until this change of view, an equation in terms of molecules 
represented the goal of the chemical investigation of a reaction. 
Now, the successive stages or development of the chemical change, 
the energy-change involved in it, and the rate'o.t which it progresses 1 
are the subject of exact investigation ; while more biologically still, 
a study is made of the conditions under which it occurs and of the 
effect upon it of variation of external conditions (temperature, 
light, etc.) and of the effect of the presence of other material 
substances (such as solvents and katalytic agents) upon its rate or 
nature. 2 Here we have a close historical parallel with the primary 
lines on which the physiological phenomena of the living plant have 
been investigated. 
Let us consider a single simple reaction. The chemist is no 
longer satisfied with knowing that 2H 2 + 0 2 = 2H 2 0, but the 
temperature conditions required to bring this change about are 
determined. In a glass vessel the gases must be heated to 448 n C 
before there is any formation of water: in a silver lined vessel 
182"C is sufficient: in contact with finely divided Platinum-black, 
union begins at 50 n C, while in the presence of colloidal Platinum 3 
the union is vigorous at the ordinary air-temperature. All these 
agents which, by their presence, cause the reaction to go on more 
quickly than it otherwise would, are called katalytic agents. They 
are not destroyed by their activity, so a trace of them will in time 
1 Most reactions that the student of chemistry has to deal with 
take place so quickly, when the reacting bodies are once 
mixed, that they may be regarded as instantaneous. Many 
organic reactions, as those of hydrolysis, saponification, and 
fermentation take place at a very slow rate which can easily 
be exactly measured. All the important metabolic chemical 
changes of living cells appear to be essentially slow re¬ 
actions. 
2 See for example, Mellor, Chemical Statics and Dynamics, 1904, 
pp. 1 and 2. 
3 This is metallic Platinum in a very fine “ ultramicroscopical ” 
state of division. It is produced as a permanent suspension 
in water by electrolysis of solutions of certain salts of 
Platinum. It appears perfectly homogeneous and clear to 
the eye, but lacks all the characters of a true solution. 
Bredig, Anorganische Fermente, Leipzig, 1901. 
