30 BORDER LINES OF KNOWLEDGE 



have the combination ABC, or fibro- cartilage. Again, 

 the bones were once only gristle or cartilage, A B. 

 To give them solidity they were infiltrated with stone, 

 in the form of salts of lime, an inorganic element, so 

 that bone would be spelt out by the letters A, B, and Y. 

 If from these organic syllables we proceed to form 

 organic words, we shall find that Nature employs 

 three principal forms ; namely. Vessels, Membranes, 

 and Parenchyma, or visceral tissue. The most com- 

 plex of them can be resolved into a combination of 

 these few simple anatomical constituents. 



Passing for a moment into the domain of Pathologi- 

 cal Anatomy, we find the same elements in morbid 

 growths that we have met with in normal structures. 

 The pus-corpuscle and the white blood-corpuscle can 

 only be distinguished by tracing them to their origin. 

 A frequent form of so-called mahgnant disease proves 

 to be only a collection of altered epithelium-cells. 

 Even cancer itself has no specific anatomical ele- 

 ment, and the diagnosis of a cancerous tumor by the 

 microscope, though tolerably sure under the eye of 

 an expert, is based upon accidental, and not essential 

 points, — the crowding together of the elements, the 

 size of the cell-nuclei, and similar variable characters. 



Let us turn to Physiology. The microscope, which 

 has made a new science of the intimate structure of 

 the organs, has at the same time cleared up many 



