528 PROTOPLASM 



may be habitable. The formation of planets, in particular life- 

 supporting planets, may be the usual course of events for other 

 stars, just as it has been for our star — the sun. Possibly a 

 planet on which life can exist is a very rare occurrence, but the 

 astronomer J. G. Porter says, with a touch of irony, "Surely 

 the success of the noble experiment of life on the earth has 

 not been so notable that we may not hope for better results 

 elsewhere." 



The question whether or not living protoplasm can be arti- 

 ficially produced is one upon which many biologists have specu- 

 lated and usually energetically answered in the negative. We 

 must grant the possibility of doing it, with sufficient knowl- 

 edge, but he who claims that protoplasm can be made in the 

 laboratory, now or at some later time, might better ask a child to 

 construct a chronometer. 



Our last question is Wherein lies the distinction between the 

 living and the nonliving? This cannot be answered with any 

 more success than have been the other questions. It is not 

 usually difficult to point out that which is living and that which 

 is nonliving, but to say wherein the difference lies is quite another 

 matter. Reactions that we are in the habit of associating with 

 life are, on analysis, usually found to be typical of nonliving 

 systems as well. Locomotion, respiration, growth, irritability, 

 self-repair, and, in a broad and crude way, even reproduction 

 and memory can be duplicated in nonliving systems. Thus, 

 charcoal respires in so far as it can combine oxygen with carbon 

 and form carbon dioxide. Indeed, the similarity is even greater 

 — when oxalic acid is shaken with blood charcoal, the acid is 

 oxidized. The charcoal acts catalytically, and not only this; 

 it may be anesthetized — poisoned — by cyanide and inhibited 

 by methane just as are living cells (page 179). The analogy is 

 not merely a superficial one; there is some common factor 



involved. 



Other processes that appear to be characteristic of living mat- 

 ter are also common to nonliving matter. Crystals grow. The 

 self-repair of a "wound" is accomplished by the Traube precipi- 

 tation membrane (page 185). A kind of "memory" exists in 

 jellies (see page 145) where a previous event determines present 

 action. Such analogies are often inexact, but equally often they 

 give us precise counterparts and in any case bring out, what is 



