268 



SCIENCE, 



[Vol. V., No. 113. 



THE RELATIONS OF MICROBES TO LIFE. 



Owing to the fact that some microscopic 

 organisms have been shown to play an impor- 

 tant part in many forms of disease, we are 

 somewhat in the habit of looking upon such 

 organisms in general as our enemies, forgetting 

 many useful purposes which they serve. One 

 of the most important processes taking place 

 on the surface of the globe is the destruction 

 of such organic masses as have been the seat 

 of life, but which have suffered death. We 

 have only to think for a moment what the re- 

 sult of a stopping of this destructive process 

 would be, in order to gain a vivid impression 

 in regard to its importance. The living thing 

 can resist the destructive forces. When life 

 ceases, the resisting-power is gone ; and, how- 

 ever complex the materials ma} r be of which 

 the organism is made up, they are quickly con- 

 verted into simple and stable substances. The 

 chief products of the changes are carbon di- 

 oxide, water and ammonia, all of which are of 

 high importance, as from them again, under 

 the influence of life, are elaborated the com- 

 plex materials. Now, we know, that, in the 

 breaking-down of organic matter after death, 

 microscopic organisms play a principal rdle. 

 They are the efficient scavengers of the earth. 

 They effect the transfer of the oxygen of the 

 air to the substances to be destroyed, and 

 thus convert useless organic matter into that 

 which is useful. 



We thus see, that, while there are microbes 

 which cause disease, there are others constantly 

 at work keeping the conditions favorable to 

 life. Recently the suggestion has been made, 

 and by no less an authority than Pasteur, that 

 the changes which are involved in the life-pro- 

 cess of both plants and animals are probably 

 intimately associated with the activit}^ of what 

 ma} T be called life-microbes. Pasteur read 

 before the Academy of sciences a paper by 

 Duclaux, in which some experiments upon the 

 growth of plants in sterilized soils are de- 

 scribed. Duclaux's paper begins thus : "The 

 destruction of the organic matter of the soil 

 by microbes, and the production of a new vege- 



tation on the soil, are two phenomena which 

 always accompany one another. Is there any 

 necessaiy connection between them ? Through 

 the labors of Pasteur, we know that microscopic 

 beings can only live at the expense of complex 

 materials elaborated by the plant with the aid 

 of chlorophyl. Can the plant develop in the 

 absence of microscopic beings ? in other words, 

 can it, without their aid, utilize the organic 

 matter left by the plant which preceded it on 

 the soil?" 



With the object of attempting to answer this 

 question, Duclaux experimented upon peas and 

 beans. These were freed from germs, sown in 

 a soil which was free from germs, and supplied 

 with organic matter of a kind which one would 

 naturally expect to be easily assimilated. The 

 result was, that after one or two months the 

 organic matter was found to be unchanged, 

 and the plants did not thrive an}' better than 

 when placed in distilled water. 



Pasteur, in commenting on these experi- 

 ments, takes occasion to suggest to Duclaux 

 an experiment on the role which microbes play 

 in animal life. The experiment is this. A 

 hen's egg^ from the surface of which all germs 

 have been removed, is to be hatched in a ster- 

 ilized space, fed with sterilized food, and sup- 

 plied with sterilized air. Pasteur believes that 

 the result will be that the chick will not live, 

 and, in general, that life is impossible without 

 the co-operation of microbes. 



We must bear in mind that this is merely a 

 suggestion, and that it rests at present upon 

 no experimental evidence. Experiments of 

 the kind suggested will involve great labor 

 and the greatest accuracj^. It cannot be de- 

 nied, that, whether the results should prove 

 favorable or unfavorable to the view of Pasteur, 

 they would be of the highest interest to the 

 chemist and biologist. 



THE CLIMATE OF THE EGYPTIAN 

 SUDAN. 



In so vast a region of country as the Egyp- 

 tian Sudan, extending as it does over about 

 sixteen or eighteen degrees of latitude and as 

 many of longitude, with differences of alti- 



