326 REPORTS ON THE STATE OF SCIENCE.—1913. 
personified and has displaced the other gods in high Olympus. Many of the 
adherents of the new god have assigned to it an immanence of which Darwin 
did not dream. They believe it to be universal and all-powerful, and that the 
partisans of any other principle are like the ignorant heathen, bowing down to 
wood and stone. One of the disadvantages of this pathological distortion of 
Darwinism is not only that it has misled the elect, but has given a welcome 
opportunity to the crafty depreciators of the achievements of science, and to the 
clamorous advertisers of new theories. In attacking the excrescences of Dar- 
winism, they persuade themselves and try to persuade others that they are 
establishing the bankruptcy of science, or clearing the way for their own nostrum. 
I believe it to be historical truth that Darwin convinced the world of the 
fact of evolution by his exposition of the principle of natural selection, that 
no principle has been suggested before or since more in harmony with the 
observed facts of nature, or more congruous with the processes of human intel- 
ligence. Using for a moment the erroneous language of personification, which 
is so convenient to employ and so difficult to avoid, I believe that natural 
selection has been the active agent in bringing about evolution, and that in a 
sense it may be said to have produced the material on which it acts by the 
processes of summation and obliteration. But Darwin never even suggested that 
all characters came into existence because they were useful, that the marks by 
which systematists find it convenient to distinguish species must be useful, or 
that the initial stages of a new character must be useful. Living beings are 
limited or determined by their inherited structure, by the inevitable necessities 
of their mode of growth and mode of living. Their parts and functions are 
linked by a thousand correlations, structural and functional, so that a change 
in any organ reverberates through the system. Living beings abound in 
characters and qualities of which no utilitarian explanation is possible. Such 
characters may be associated with other characters that are useful; they may 
have been useful in the past, in a different environment; they may never have 
had ‘selection-value,’ but a change in the environment or an alteration in the 
kaleidoscopic interrelations of the whole organism may give them ‘selection- 
value.’ They are material ready for natural selection, and so far from being 
vague and inchoate, may have a high degree of definiteness and complexity. 
I propose to invite your attention to some examples of characters and qualities 
that, so far as we can see, are not present because they are useful. 
The process of oxidation always accompanies living activity, and some of the 
chemical energy is liberated in the form of heat. Probably in plants and in the 
animals that we speak of as ‘cold-blooded’ the discharged heat is practically 
a waste product. The temperature of the tissues must be above freezing-point 
for the vital processes to be active, and each kind of organism has a euthermal 
range, a few degrees of temperature within which its organic processes succeed 
best. The heat produced by internal oxidation, however, does not appear to 
contribute in any important respect to the production or maintenance of the 
requisite temperature. Most organisms are ruled by the surrounding media, 
their activities rising and falling with the external temperature. If they have 
the power of movement or locomotion, they may turn or crawl to the sun, or seek 
the shade, but changes of weather and the recurring seasons are the dominating 
factors in their lives. Even the higher reptiles depend directly on the circum- 
ambient media. A few years ago, we improved the heating-system in the London 
Zoological Gardens, with the result that there was an increase in the frequency 
with which the reptiles fed, and a rise in their activities. If you wish a little 
torpid water-tortoise or a young alligator to take food, you must place it in a 
warm bath, precisely as many chemical reactions will not take place until you 
heat the mixture over a spirit-lamp. 
Birds and mammals, the ‘ warm-blooded’ creatures, have a fixed and rather 
high euthermal state, and depend chiefly on their internal production of heat to 
produce it. The normal temperature of the human body is 98°4° Fahr., and this 
may be taken as a fairly typical mammalian temperature, the normal for birds 
being a little higher. There is no more certain indication of illness, of the 
existence of something wrong in the bodily functions, than an important rise or 
fall in the temperature, and we feel ill even when the variation is small. Cer- 
tainly we take notice of changes in the surrounding media, and after a time may 
be affected by them, so that we try to avoid extreme heat and extreme cold. 
