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to be considered. Thus, dissection is to be recognized as a method 

 of displaying structure of a gross and special kind. It consists in 

 the orderly exposure and displacement of organs with the object 

 of observing their features and relations to surrounding parts. 

 The plan is essentially one of analysis, since conceptions of structure 

 are based on the recognition of differences, the latter being estimated 

 1>\ various features, such as form, color, texture, or position. On 

 the other hand, because of the class of structure with which it deals, 

 dissection is also to be recognized as a preliminary method in 

 comparison with various others involving the use of the microscope. 



THE INTERPRETATION OF STRUCTURE. 



( iross structure is, in a sense, only the outward, expression of the 

 finer microscopic structure underlying it, the latter being the true 

 basis of the body. This refers not so much to the individual 

 features of the organs as to the relation existing between their 

 appearance as gross objects and their tissue composition. Since 

 this relation is more fully discussed below under the head of general 

 anatomy, it need only be mentioned here as an element in the 

 interpretation of structure as viewed from the gross standpoint. 

 All animal structure, however, may be considered from two points 

 of view physiological and morphological. 



The physiological aspect of structure concerns the functions 

 or activities of the living organism and of its individual parts. The 

 contraction of a skeletal muscle is a change in the axial relations of 

 living protoplasm, but the form and connections of the muscle are 

 such that the contraction results in movement of one bone upon 

 another. The excretion of urine on the part of the kidneys is the 

 final stage of a process which rids the body of soluble waste nitro- 

 genous materials by discharging them into a system ot tubes 

 connected with the outside of the body. What is important in 

 these, as in a multitude of analogous cases, is that structure and 

 function are intimately related, and in point of interpretation, 

 serve to explain one another. 



The morphological aspect of structure concerns various 

 features of form and arrangement which, although they have been 

 developed on a ba>is of utility, cannot be explained, directly on that 



