vi INTRODUCTION 



a technique of micro-chemistry. It is not too much to say that 

 the results of genetical researches are now full of trivial detail, 

 are rather dull and have little of far-reaching theoretical signifi- 

 cance. Biochemistry, while not revolutionary, is full of interest- 

 ing and stimulating materials : such are, for instance, the 

 results of researches on vitamins and hormones and on rejuvena- 

 tion. Without doubt much more in these directions may be 

 expected in the near future. 



The present phase in biology is to be regarded as essentially 

 a critical-constructive one. The hypotheses of transformism, 

 natural selection, Lamarckism, etc., are being '' tried-out " and 

 no one can say what is going to replace them. Not only the 

 " Weismannism " of a former generation, but also the " Mor- 

 ganism " of to-day have proved unsatisfactory, although (of 

 course) these investigations have left their marks on our science. 

 Practical genetics is an old affair. In these lines of research a 

 return to the old-fashioned natural history of the period of 

 Darwin and Wallace is already indicated. Naturalists have been 

 regarded as " scientists by courtesy," but much promise lies in 

 the study of ecology — of organic habits in the wild. (Too much 

 has been based on experimental work on the laboratory domestic 

 animals !) The older, cruder materialism which emerged from 

 the physiology of the medical schools has proved unsatisfactory 

 when tested in the light of modern thermodynamical theory and 

 we do not really know, in the least, what is going to replace it. 

 A survey of biological science gives us certain indications that 

 its growing-point, at present, is in biochemistry and that this 

 growth of significant theoretical knowledge will be accelerated 

 when it will have been possible to press new physical results 

 into the service of biology. 



It is very curious to notice how little the revolutionary, 

 experimental methods of present-day physics have affected 

 practical biology — and how much less speculative, mathematical 

 physics has changed the attitude of speculative biology. Radio- 

 active transformations seem to be affairs of inorganic chemistry. 

 The annihilation of matter is said to go on in the interiors of 

 hot stars and the creation of matter may, we are told, be pro- 

 ceeding in cold inter-stellar space, but there is no hint that 

 these changes have any significance for the complex organic 

 system of things. Electro-magnetic fields of force exist every- 



