xvi THE HISTORY OF ZOOLOGY 649 



branch-work with the most complex and often puzzling inter- 

 relations. 



Among the numerous recent contributions to philosophical 

 Zoology it must suffice to mention the works on heredity and 

 kindred subjects of August Weismann. the most prominent 

 member of the ultra-Darwinian school, who deny use-inheritance 

 and rely upon natural selection as the main if not the sole factor 

 in evolution. The opposite view, which accepts the truth of use- 

 inheritance, is mainly supported by the American school of Neo- 

 Lamarckians. Weismann has also resuscitated the theory of 

 pre-fonnation under a modern form. He considers that the 

 various parts of the adult organism are represented in the 

 chromation (germ-plasm) of the sex-cells by ultra-microscopic 

 particles or determinants. 



In a brief sketch like the present it is impossible to do more 

 than refer, in general terms and without mention of names, to the 

 vast amount of work now being done in every department of 

 Zoology. The output of original research is greater than at any 

 former time and is increasing rapidly, and every important addition 

 to our knowledge necessitates a more or less thorough reconsidera- 

 tion of the general and special problems of morphology and 

 classification. Attention, must, however, be drawn to the 

 researches of the last few years in the departments of experimental 

 and statistical Zoology. Exact observations on comparative 

 physiology, on the precise nature of the action of external con- 

 ditions, on the physiology of the cell, on the conditions influencing 

 the development and growth of the embryo, and on the limits and 

 characteristics of individual variation, are new fields of study in 

 which it may safely be said that the greatest promise of the future 

 lies. 



In conclusion, it must be pointed out that in order adequately to 

 solve the problems of Zoology they must be approached from all 

 sides. From the time of Cuvier to that of Owen comparative 

 anatomy was the dominant branch of the science, and there was 

 a tendency to depreciate the work of the " mere " systematist and 

 outdoor naturalist. For the last five and twenty years embry- 

 ology has been in the ascendant, and the " mere " anatomist has 

 been somewhat overshadowed. To-day, hopeful signs of a 

 renewed interest in ethology the study of living animals under 

 natural conditions are accompanied by a tendency to look upon 

 all laboratory work as necrology rather than biology the study 

 of corpses rather than of living things. But nothing is more 

 certain than that if the new " natural history " is to be superior to 

 the old more scientific, more concerned with the solution of 

 general problems it can only be by utilising to the full all that 

 has been learnt in the laboratory in the departments of anatomy, 

 physiology, and embryology. 



