THE ORIGIN OF BACTERIA AND OTHER MICRO-ORGANISMS 2$ 



affirmative. Spores of higher fungi and of lichens have survived herba- 

 rium conditions for many years, according to some authorities, for nearly 

 IQO years. Endospores and some of the filterable viruses are known to 

 survive for several years and longer, in cloth, in dry dirt and in paper. 

 The microscopical examination of the cloth of Egyptian mummies showed 

 the presence of numerous spores of some mold, also endospores of bacteria, 

 and bacteria, apparently in good morphological condition. Some of these 

 apparently developed when introduced into gelatine media, though it was 

 also evident that most of them had lost the power to germinate or to 

 septate. In interstellar space the conditions are almost ideal for the 

 preservation of the life of micro-organisms in the resting stage. There is 

 absence of oxygen of moisture and the temperature is very low (perhaps 

 less than 220 F.)'. It is true they are exposed to light, more especially 

 the chemically active ultraviolet rays, but even these are checked in their 

 destructive action on life because of the absence of warmth, moisture and 

 of atmospheric oxygen. There is, therefore, no plausible reason why the 

 minute particles detached from the meteoric mass should not be carried 

 through cosmic space by the radiation pressure of sunlight. This radiation 

 pressure would, however, act only in one direction within our solar system, 

 namely, in the direction away from the sun. This force could therefore 

 transport germs to the earth from Mercury, Venus, Moon and such 

 meteoric and other heavenly bodies which move between the earth and the 

 sun. None could reach us from Mars, Neptune or Jupiter, unless perhaps 

 through the radiation pressure of light reflected from these planets but since 

 only an infinitely small amount of reflected light reaches us from these 

 sources the likelihood of this carrying life to the earth is correspondingly 

 slight. However, the radiation pressure from a neighboring sun might 

 carry germs to the planets of our system. 



Very naturally the question arises how may spores and other similarly 

 small organisms get away from the so-called force of gravity which holds all 

 substances of a planet together and attracts matter in space to its surface. 

 Air currents could readily carry these particles to the upper air zone but 

 could not project them beyond. Arrhenius assumes that the electrical 

 currents of the earth, more especially the negative currents of the north 

 pole, are more than sufficiently strong to carry very small particles against 

 the force of gravity and it is suggested that these electrical currents are 

 constantly scattering innumerable spores and germs into cosmic space. 

 These can never reach the sun because in time, in their flight toward that 

 body, the radiation pressure of light will arrest them and even turn them 

 back upon their own path. 



The following is quoted from the book by Arrhenius : 



"In the vicinity of solar bodies seeds would be checked in their cosmic 



