232 
chemistry and physics with huge success to the study of living organ- 
isms, and one obstacle after another has been broken down until in 
the impetus of their success they have become almost all pronounced 
mechanists and have claimed the sufficiency of chemical and 
physical explanations for all the phenomena of life. The biologists, 
too, have been carried away and we see the mechanistic view put 
forward very strongly by Huxley, whilst more modern dis- 
coveries have led to the very extreme views held by Jacques Loeb. 
The modern work in experimental embryology has led in some cases 
to the belief that development of the organism is explainable by 
known physico-chemical laws, but many of the foremost exponents of 
this branch of biology are unable to agree with this and one of 
them, Driesch, is now, perhaps, the foremost advocate of a new 
vitalism. Bergson, whose philosophy has aroused fresh interest to- 
•day wherever it has been studied, “rising into heights of meta- 
physics” proclaims that our conceptions of mechanism fail to ex- 
pdain life. There is a spirit of unrest abroad once more and we meet 
again a tendency here and there to consider the organism as some- 
thing more than a machine. The old phrase Vital Force is, however, 
often disguised and appears in new form as Biotic Energy, En- 
telechy, Elan vitale, etc., although it must not be supposed from this 
that the terms mean exactly the same thing. It must be confessed 
that the exponents of new vitalistic theories are being subjected to 
a strong frontal attack, and the feeling of the other side is summed 
up pretty well in the following quotation from a work on embry- 
ology published very recently. 1 2 “Thus we are brought back to Pre- 
Darwinian days, to a position indeed more primitive than that of 
the early 19th century, for it is surely easier to conceive of an all 
embracing intelligence, whose myriad plans were realised in the 
different species, rather than of millions of uncaused and unrelated 
intelligences Driesch offers no explanation whatever, and it 
seems to us that this final result is the reductio ad absurdum of his 
whole system.” Verworn, the physiologist, writes 3 : “But so much is 
certain; an explanatory principle can never hold good in physiology 
with reference to the physical phenomena of life that is not also 
applicable in chemistry and physics to lifeless Nature. The assump- 
tion of a specific vital force is not only wholly superfluous but inad- 
missible.’’ One other example and that comparatively recent. I have 
no doubt that many of you have Schafer’s Presidential Address to the 
British Association at Dundee in 1912 still in your mind. In the 
course of his remarks on the sufficiency of physics and chemistry, 
he stated “Vitalism as a working hypothesis has not only had its 
foundations undermined, but most of its superstructure has toppled 
over, and if any difficulties still persist, we are justified in assuming 
that the cause is to be found in our imperfect knowledge of the con- 
stitution and working of living material ” I want to emphasise the 
1. MacBride. Text-Book of E • bryology., Vol. I., Envertebrata. London, 1914. 
2. Verworn, General Physiology (Eng. Trans.). London, 1^99. 
