Preface. vii 



ing elimination ; but we cannot alter a law which, as that 

 of one of the factors of organic phenomena, still obtains, 

 notwithstanding the introduction of other factors. 



However profoundly the laws of phenomena may be 

 modified by such introduction of new and higher factors, 

 the older and lower factors are still at work beneath the 

 surface. And he who would adequately grasp the social 

 problems of our time should bring to them a mind prepared 

 by a study of the laws of organic life : for human beings, 

 rational and moral though they may be, are still organisms ; 

 and man can in no wise alter or annul those deep-lying 

 facts which nature has throughout the ages been weaving 

 into the tissue of life. 



Some parts of this work are necessarily more technical, 

 and therefore more abstruse, than others. This is especially 

 the case with Chapters III., V., and VI. ; while, for those 

 unacquainted with philosophical thought, perhaps the last 

 chapter may present difficulties of a different order. With 

 these exceptions, the book will not be beyond the ready 

 comprehension of the general reader of average intelligence. 



I have to thank many kind friends for incidental help. 

 Thanks are also due to Professor Flower, who courteously 

 gave permission that some of the exhibits in our great 

 national collection in Cromwell Eoad might be photographed 

 and reproduced ; and to Messrs. Longmans for the use of 

 two or three illustrations from my text-book of "Animal 

 Biology." 



C. LLOYD MOEGAN. 



UNIVERSITY COLLEGE, BRISTOL, 

 October, 1890. 



