INTRODUCTION 13 



names which go far to denote the region where each is 

 discovered. 



The nervous tissues are far less conspicuous in an 

 anatomic sense than the three orders just enumerated. 

 Let us imagine for a moment that each of the four 

 divisions in which we have placed the tissues could be 

 presented separately to view. Four human figures would 

 appear before us. That one composed wholly of connect- 

 ive tissue would consist of the skeleton as a basis, and 

 would show, in addition, an indication of each organ in 

 outline, with an internal system of interlacing strands. 

 It would include the ligaments which join bone with bone, 

 the cartilages which also occur about the joints as well as 

 in some other localities, and the tendons uniting muscles 

 with bones. The muscles themselves would be blocked 

 out in this picture by the surface membranes which they 

 possess and by webs of non-contractile material within. 



The second figure would retain the complete contour 

 of the human form, inasmuch as it would have the skin. 

 If it were transparent enough the cavities and external 

 surfaces of the viscera would be seen defined in their 

 entirety, but with spectral lightness. The alimentary 

 canal would be traceable as a winding tube of great deli- 

 cacy within another still more diaphanous. The blood 

 system would be mapped in similar fashion. The interior 

 arrangement of each gland would show a tree-like pattern 

 of bewildering intricacy. 



The third figure, consisting of the contractile tissues, 

 would be fragmentary and discontinuous. To <;>neeive 

 of this apparition as keeping its shape calls for an extra 

 stretch of the imagination. It would supply the chief 

 bulk of the muscles and a fraction, missing in the other 

 manikins, of the alimentary, circulatory, and reproductive 

 systems. In a scattering way contractile tissue occurs 

 even in the skin, where its presence makes possible the 

 "goose-flesh" reaction. Although this third figure would 

 be less coherent than the others, it would greatly exceed 

 them in weight. 



