THE CELL. 3 



it is called human physiology, for the great and ultimate end and aim 

 of all physiological studies is the understanding of the functions of 

 ourselves. Morphology and physiology are treated as though they 

 were absolutely distinct sciences, yet they are so closely related that 

 the division is made only for convenience. 



Morphology includes in its category such subdivisions as anat- 

 omy, histology, and embryology. 



Anatomy is the science that treats of the situation, form, and 

 structure of the various parts of the organism. Anatomy from its 

 root keeps in mind the idea of cutting or dissecting, and as com- 

 monly used at the present time deals with the grosser work done 

 upon the more common and apparent structures of the body with 

 scalpel and forceps. When we describe in all their detail the different 

 organs of the body and the position of the organs to one another, we 

 call it descriptive anatomy. 



Contrasted with anatomy is histology, sometimes called micro- 

 scopical anatomy. Histology is the science that deals with the inti- 

 mate structure of the various tissues of an organism. It takes up 

 the work where anatomy ends; as it brings to its aid the microscope, 

 it can delve down deeper and deeper until it gives us knowledge of 

 the component parts of the various organs. Histology is a tissue- 

 study. Its separation from anatomy is only for convenience, and is 

 not absolute. 



Embryology is the science of the development of the adult from 

 the ovum or germ. It gives a history of the various stages of develop- 

 ment from the moment of impregnation of the ovum, until the adult 

 is reached. Its field is more closely associated with morphology 

 than physiology. 



Living things are usually found in separate masses and these 

 have peculiarities and structures of their own which give to them 

 the name "organisms." This is true equally of the large masses, 

 such as the elephant or whale, as of the small bodies found in water 

 or the bacteria of disease. All the structures of the latter have as 

 yet not been discovered nor dissected, as it were, since the microscope 

 is not powerful enough and our supply of reagents not adequate 

 enough to lay bare all of their properties and forms. 



When we examine some of the contrivances found in the mechan- 

 ical world, such as a watch or a machine, they at first sight appear 

 to us, as regards their identity, single individual units; that is, as 

 one watch or as one machine, each capable of doing its own peculiar 

 work. Upon closer investigation, we perceive that each is com- 



