WHAT IS A LIVING ANIMAL? 289 



WHAT IS A LIVING ANIMAL? HOW MUCH OF 



IT IS ALIVE? 



By Dr. A. F. A. KING 



WASHINGTON, D. C. 



CONSIDERING the second question first, the reply to it will depend 

 a good deal upon education. An extremely ignorant person 

 might answer that all parts of a living body are alive except the bones. 

 It required some education before we medical men learned to realize, 

 without surprise, that crude metallic bodies — bullets, pins, needles, wire 

 sutures buried in our internal organs, nails driven into our fractured 

 bones by surgeons, finger rings, scissors, forceps, spectacles, etc., left in 

 the peritoneal cavity by careless operators — could remain in a human 

 body without any immediate danger to life. 



We had to learn also that large crystalline masses — the various 

 forms of calculi — and dead foetuses; lithopodians ; even dead children 

 at full term, both intra- and extra-uterine — could remain in a living 

 body for several decades without any immediate danger to life. Thus 

 we learn from these crude examples that living bodies may contain dead 

 bodies, and dead substances of various kinds. Numerous other in- 

 stances will now be considered. 



The protective shells of some animals, the epidermal appendages 

 (horns, tusks, hoofs, claws, nails, hair, wool, etc.), of others, are only 

 alive at their proximal ends — their " roots " so-called. Their distal 

 extremities are not living. They are products of life, but so are our 

 coal beds, chalk cliffs, coral reefs and tortoise shell combs, but they are 

 not alive. 



If we ask, Where is the line of division between the dead and living 

 in a cow's horn, or an elephant's tusk, we must reply, there is no such 

 line. The transition from living to dead tissue is a gradational one. 

 And this simple example should help to dispel the common error that 

 everything in this world must be either dead or alive. Not so. It may 

 be between the two : neither one or the other. Here, if anywhere, the 

 old truism, Natura non facet saltern, deserves special recognition. 



We must certainly realize that the gases, foodstuffs and exeremen- 

 titious matters in the alimentary canal and the contents of the urinary 

 bladder are not alive. Is the bile living? Bile is an excrement from 

 the hepatic cells, the histological units of the liver, which find it neces- 

 sary to discharge their toxic excreta into those minute drains, the bile 

 ducts, and thence into the main sewer of the intestine. In thus main- 

 taining their own normal metabolism, they save us from hepatic 

 toxaemia. Bile is not alive. 



VOI,. LXXV. — 19. 



