BIOLOGICAL SCIENCES 3 



has grown into a science quite apart from any particular bear- 

 ing on human affairs. Cytology is the science dealing with 

 the ultimate units of structure of living things cells and 

 has both physiological and morphological sides, while, in 

 connection with the germ cells, it comes in intimate con- 

 tact with the fundamental problems of general biology. His- 

 tology deals with the aggregates of cells in tissues, and this 

 branch, again, is mainly important to students of medicine. 

 Pathology deals with abnormal structures and functions 

 of animals and plants, and is essentially a science of dis- 

 ease. Palaeontology deals exclusively with past life on the 

 earth as revealed by fossil forms of plants and animals. Taxo- 

 nomy is the science of classification and is dependent upon 

 anatomy, embryology and ecology. 



The sciences enumerated above are mainly morphological 

 or based upon the structures of living things, that is upon 

 the mechanisms employed in the performance of vital ac- 

 tivities. The remaining five branches are essentially physiolog- 

 ical or based upon the actions of the living mechanisms. 

 In this group the science of physiology is the oldest and the 

 best established, dealing, as it does, with the fundamental 

 activities of digestion, assimilation, respiration, excretion, 

 secretion, nerve response and reproduction. Experimental 

 biology, ecology and genetics are more recent and have been 

 developed in connection with the attempts to throw light upon 

 the fundamental biological principles of growth, differentiation, 

 inheritance, variability and organic relationships. Ecology 

 deals with animals and plants as affected by environment, 

 distribution on the earth's surface, and the like. Genetics 

 deals with the different phases of the problems of heredity. 

 Neurology, finally, including psychology, is a science deal- 

 ing with the nervous system and with the attributes of the 

 brain, while a corresponding science deals with the phenomena 

 of sensation, irritability, etc., in plants. 



Other sciences such as Sociology, Anthropology, Political 

 Economy, etc., dealing with man, have a certain claim to 

 relationship with the biological sciences, but, except in a very 



