io The Science of Life. 



.save the science from self-conceit by their emphasis on 

 the partial nature of all physiological analysis. 



Bionomics has risen in dignity by a realization of its 

 evolutionary importance. From being- an emotional 

 student of habits, or an inquisitive collector of the 

 "curiosities of animal life", the open-air observer and 

 explorer has become an important contributor to the 

 theory of adaptation and struggle, or to animal psy- 

 chology. 



In regard to heredity, the most important steps have 

 been: (a) The formulation of the doctrine of the con- 

 tinuity of the germ-plasm (Weismann); (b) The growth 

 of scepticism as to the transmissibility of acquired 

 characters (Weismann); (c) The accumulation of evi- 

 dence pointing to the conclusion that the chromatin of 

 the nuclei is the chief bearer of hereditary qualities 

 (Hertwig), and the proof that the chromatin of the 

 fertilized egg-cell consists in equal parts of paternal 

 and maternal chromatin, which are equally distributed 

 in the subsequent cell-divisions; and (d) The law of 

 ancestral inheritance, due to Galton. 



In regard to the primary or originative factors in 

 evolution, those namely which give rise to variations, 

 some progress has been made, though the problems are 

 still far from solution, (i) Some clearness has been 

 gained by defining the distinction between congenital 

 variations due to changes in the germinal substance 

 and modifications which are wrought upon the body as 

 the results of change in function and environment. 

 (2) Some excellent experimental work has been done in 

 the artificial production of modifications. (3) A great 

 service has been rendered by Mr. Bateson in his Mate- 

 rials for the Study of Variation, which contains an ex- 

 haustive account of observed instances of a certain kind 

 of variation, and affords some evidence of the occur- 

 rence of what is called "discontinuity" in evolution. 

 (4) The statistical study of variations, developed by 

 Mr. Galton and Profs. Weldon and Pearson, marks the 

 introduction of a new method, which aims at repre- 

 senting in a curve the extent of variation in a given 

 character, and the proportion of individuals exhibiting it. 



