26 PHARMACEUTICAL BACTERIOLOGY 



flight by the radiation pressure of sunlight and tend to accumulate in 

 great numbers. The planets rotating about the suns would thus be likely 

 to receive such seeds, more especially those planets which were somewhat 

 more remote from the sun. In these positions the seeds would also have 

 lost much of their original speed and would in all probability not become 

 excessively heated, probably less than ioo° C, in their motion through the 

 atmosphere. 



"In the vicinity of the suns, the intercosmic seeds now entering upon 

 their return journey to the planets would meet with particles whose weight 

 is somewhat less than the repeUing force of the radiation pressure and 

 which for that reason have begun the return journey to the sun. Just 

 like the seeds, these small particles tend to accumulate in the vicinity of 

 the suns. 



"These very small seeds and the yet smaller particles clinging to them 

 such as spores and bacteria, would be more likely to reach the planets 

 nearer the sun. 



" In this manner Hf e may have been carried from planet to planet, from 

 solar system to solar system, throughout the ages. But, as in the case of 

 the billions of pollen grains which escape from a single oak, and which 

 are distributed by the air currents, perhaps only one will give rise to a 

 new tree; so likewise of the billions and trillions of germs which wander 

 about in cosmic space, only one may ever reach a planet where it may de- 

 velop and give rise to many new forms of life." 



According to the above idea of panspermia all of the organisms in the 

 entire universe are related and consist of cells which are built up through 

 chemical combinations of carbon, hydrogen, oxygen and nitrogen. The 

 supposition that there may be worlds in which, for example, living organ- 

 isms are formed from chemical combinations in which carbon might be 

 displaced by silicon or titanium, is highly improbable. Life upon other 

 inhabited planets is in all probability similar to that upon the earth. 



It is generally known that several planets of our solar system are closely 

 similar to that of the earth, as Venus and Mars. Mercury, like the moon, 

 turns one side to the sun at all times and hence the sides have a constant 

 temperature, one side hot and the other cold, one side in constant 

 darkness and the other constantly illumined. 



Even admitting that the idea of panspermia is well founded and that 

 very minute forms of life can be transmitted from one planet to another, the 

 question of the origin of life still remains unanswered. We have merely 

 pushed the problem into a dark corner. By relegating the matter to one 

 or many distant planets we have not thereby escaped the responsibility of 

 the final scientific proof and unimpeachable explanation of the origin of life. 



Bacteriologists have from time to time commented upon the fact 



