264 HIGH SCHOOL ZOOLOGY. 



dence is in part due to the differences which we shall refer to 

 hereafter. However great these differences are, it must, never- 

 theless, be understood that the resemblances between plants and 

 animals ai-e such, that the methods of Zoology are the same as 

 those of Botany, and the aspects of the study of the Biology of 

 plants, the same as those of the Biology of animals. 



VARIOUS ASPECTS OF BIOLOGICAL STUD^. 



(1) Morphological. 



5. This division of Biological study involves, as we havfe 

 seen, questions of form and structure. It admits of sub-division 

 according as these questions deal with the adult, or with stages 

 in the development of the adult : Anatomy, in its widest sense, 

 being the term reserved for the former group of questions, 

 Embryology oi- Ontogeny for the latter. In a narrower sense, 

 Anatomy is restricted to such structural points as can be 

 studied without the aid of the microscope, while Histology is 

 em[)loyed for the study of the finer details of the tissues, and 

 Cytology for those of their component cells. It is evident that 

 questions, other than those of pure form, must be inseparable 

 from the studies which have just been styled morphological. 

 The changes of form, for example, in individual cells are merely 

 the expression of physical and chemical changes taking place 

 within them, so that Cytology might as legitimately be referred 

 to the following aspect of Biological study. 



(2) Physiological. 



6. Morphology is sometimes described as statical Biology, 

 because it involves the notion of rest ; Physiology, on the 

 other hand, as dynamical, because it studies the work- 



