THE STUDY OF BACTERIA. 



The bacteriologist is working in a 

 wonderland fully as remote to the aver- 

 age mind as that ever occupied by the as- 

 tronomer or psychologist ; and yet it is 

 as real to him as though he were walking 

 through a forest and noting the different 

 kinds of trees. Such popular doubts as 

 have been held regarding bacteriology 

 and even the existence of bacteria are no 

 longer justified. The evidence is too 

 overwhelming not to be accepted by any- 

 one who has sufficient interest to investi- 

 gate. The methods used in bacteriologic 

 studies are to-day giving us information 

 fully as concise as that obtained by the 

 general botanist in the study of higher 

 plants. Indeed, the phenomena of bac- 

 terial activities and the chemistry of the 

 products of growth of many species of 

 bacteria have already received attention 

 not equaled in the study of some of our 

 most useful plants. 



Bacteria are plants ; not because of any 

 absolute characteristic that separates them 

 from animals, but because comparative 

 study shows that they are more like 

 plants than animals. They are single- 

 celled organisms and each individual has 

 the prime factors of life, assimilation, 

 growth and reproduction. Each bac- 

 terium is an independent cell and al- 

 though the cells in some species remain 

 attached to one another, giving rise to 

 characteristic groupings, they are mostly 

 detached and free individuals. Bacteria 

 can increase in numbers to a remarkable 

 extent when favorable conditions exist. 

 The mother-cell simply splits into two 

 daughter-cells and these form a genera- 

 tion of four cells, while later generations, 

 consisting of perhaps one million cells, 

 can in fifteen or twenty minutes produce 

 two million bacteria. But conditions 

 must be favorable for this active growth, 

 ample food stuffs, free from other bac- 

 teria, together with mosture and reason- 

 able warmth are most essential. There 

 are many circumstances constantly at 

 work to prevent an overgrowth of bac- 

 teria ; exhaustion of food supply, antag- 

 onism of species and fresh air with sun- 

 shine, are the most important. Bacteria 



are present everywhere in greater or less 

 numbers, except within the bodies of 

 healthy, growing plants and animals. It is 

 for this reason that bacteria become so ac- 

 tive and multiply with great rapidity 

 when once established in the tissue fluids 

 of larger organisms, either before or after 

 they have died. Vital activities during 

 health prevent the entrance of bacteria 

 into our bodies. There are, however, 

 times when the association of different 

 species of bacteria and also the associa- 

 tion of bacteria with higher plants is of 

 mutual advantage. The association of de- 

 composition and pathogenic bacteria fre- 

 quently makes it possible for the latter to 

 infect an animal, when alone it perhaps 

 would not take place. Again, the growth of 

 certain bacteria within the root-structure 

 of plants greatly improvestheir functional 

 activity. The leguminuous plants are en- 

 abled to assimilate much larger quanti- 

 ties of nitrogen when associated with bac- 

 teria than when growing alone. No such 

 mutually advantageous relationships are 

 known to exist between bacteria and ani- 

 mals; the tendencies are rather destruc- 

 tive, leading to the infectious diseases. 

 The general biologic function of the bac- 

 teria is very important and in a general 

 way the need of their existence can be 

 much better appreciated than that of 

 many living beings. Decomposition may 

 be stated as being their chief functional 

 activity. Decomposition stands before 

 life ; without it the progress of the genera- 

 tions would terminate. The gradual and 

 ever rapid disappearance of the substance 

 of vegetable and animal bodies after 

 death makes room for growing life. With 

 an absence of decomposition the bodies 

 of plants and animals would collect on 

 the earth and cover it so deeply with or- 

 ganic matter that plants in particular would 

 be entirely unable to obtain requisite 

 nourishment. Higher plants having 

 chlorophyll are able to feed on inorganic 

 material, while bacteria require organic 

 matter to sustain life. Bacterial food is 

 then derived from the higher forms of 

 life, while these higher forms feed on the 

 end products of bacterial decomposition, 



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