xvi THE HISTORY OF ZOOLOGY 669 



tion of the general and special problems of morphology and 

 classification. 



In addition to the continued study of adult structure and em- 

 bryology of animals and plants with their classification and 

 phylogeny and their distribution in space and time, the workers 

 in Biology during the first two decades of the twentieth century 

 have bestowed more attention than hitherto on (1) Experimental 

 Biology and Embryology, (2) Genetics, and (3) Cytology. It is in 

 the second of these departments the revived and intensified 

 study of heredity that the impulse towards the first and third 

 has mainly originated. A large part of the experimental work 

 accomplished has had for its object the solution of genetic problems ; 

 and on the other hand the attempts to co-ordinate the minutiae 

 of structure in the germ-cells with known phenomena of heredity 

 or theoretical explanations of such phenomena have given interest 

 and importance to most recent cytological work. 



VOL. II 



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