82 



THE POPULAR SCIENCE MONTHLY.— SUPPLEMENT. 



tency, under the proper conditions, to produce or- 

 ganisms. But, in reply to your question, they will 

 frankly admit their inability to point to any satis- 

 factory experimental proof that life can be devel- 

 oped, save from demonstrable antecedent life." « 



What is the justification for this belief that 

 non-living matter can, under proper conditions, 

 produce organisms ? 



There is a substance called acetylene, the mole- 

 cule of which is made of two atoms of carbon, 

 holding together by two hooks from each, and 

 four atoms of hydrogen each holding on by its 

 one hook to a carbon-atom. It is made by driv- 

 ing hydrogen between the tremendously hot car- 

 bon-points of an electric light; directly, there- 

 fore, from the elements. If we make acetylene 

 pass through a red-hot tube we shall get what is 

 called benzine. A molecule of benzine is a game 

 of round the mulberry-tree played by six carbon 

 atoms, each one holding by two hooks to its right- 

 hand neighbor and one to its left, while it keeps 

 the remaining hook for a hydrogen-atom. It is 

 therefore made of three molecules of acetylene, 

 each of which has dropped two hydrogen-atoms 

 in order to join hands with the other two mole- 

 cules. How does this molecule of benzine get 

 made out of the three molecules of acetylene ? 



There are two answers. If anybody likes to 

 assert that benzine can never be made out of 

 acetylene without the presence of preexisting 

 benzine, it is impossible to disprove his state- 

 ment. We should have no means of discovering 

 the presence of two or three molecules of ben- 

 zine-vapor in the original hydrogen that we made 

 the acetylene of. It is known that the first step 

 is often a difficulty in the formation of chemical 

 compounds, and that, when the process has once 

 begun, the new compound has the property of as- 

 sisting the formation of its like. Nobody knows 

 why this is. 



No chemist, however, will, as a matter of fact, 

 make this supposition about benzine. It is gen- 

 erally held that the benzine-molecule is formed 

 by the collision of three acetylene-molecules in 

 favorable positions. This collision is a coinci- 

 dence. Each molecule meets another molecule 

 many millions of times in a second ; but I am not 

 aware that anybody has calculated the number of 

 times it meets two other molecules at once. We 

 must know a great deal more of the constitution 

 of atoms before we can calculate what proportion 

 of these triple collisions is favorable to the for- 

 mation of a benzine-molecule; but there can be 

 no doubt that the coincidence takes place an enor- 

 i " Belfast Address." 



mous number of times per second in every cubic 

 centimetre of the gas, because a perceptible quan- 

 tity of benzine is obtained. 



There is another substance which can be made 

 out of six carbon-atoms and six hydrogen-atoms, 

 by fastening them together in a different way. I 

 forget the name of it, but it is an unstable and 

 explosive substance, which breaks itself up on 

 the slightest provocation. We do not find this 

 mixed up with the benzine, although the coinci- 

 dence which formed it may have occurred quite 

 as often as that which formed benzine. It be- 

 comes extinct because it is not adapted to the 

 conditions. 



On the other hand, we do find some more 

 complex compounds mixed up with the benzine. 

 These may have been partly made by collision of 

 benzine-molecules with acetylene-molecules ; part- 

 ly by coincidences of a more elaborate character, 

 such as the collision of four or five acetylene- 

 molecules. These are all stable ; that is to say, 

 they are suited to the conditions, and therefore 

 they survive. 



Observe, then, that iD this very simple case 

 of the formation of an organic body (in large 

 quantities benzine is always prepared from coal- 

 tar) it is produced by a coincidence, and pre- 

 served by natural selection. 



If we take thirteen carbon-atoms instead of 

 six, and combine them only in the simplest ways, 

 so as to form an open chain with branches, it 

 has been calculated by Cayley that 799 com- 

 pounds are possible. How many of these are 

 stable at a given pressure and temperature, no- 

 body knows. In a gaseous mixture of paraffines, 

 the coincidence necessary to form each one of 

 them may occur many thousand times a second. 

 Only those can survive which are stable under the 

 given conditions. Such natural selection deter- 

 mines, for example, the compound ethers which 

 go to make up the flavor of a pear. 



Now, those persons who believe that living 

 matter, such as proteine, arises out of non-living 

 matter in the sea, suppose that it is formed like all 

 other chemical compounds. That is to say, it orig- 

 inates in a coincidence, and is preserved by nat- 

 ural selection. Only in this case the coincidence 

 is of the most elaborate and complex character. 

 I once saw an estimate of the number of carbon- 

 atoms in a molecule of albumen. I cannot now 

 lay my hands on the book in which I found it, 

 but there were three figures in it. I do not be- 

 lieve, on the strength of that estimate, that there 

 are over a hundred carbon-atoms in a molecule 

 of albumen ; because, from the nature of the 



