MICHIGAN ACADEMY OF SCIENCE. 7 



most highly complex forms as they are broken off from the original molecules 

 to the simple elements and compounds as hydrogen, nitrogen, carbon-dioxide 

 and water, found in the final step. If it becomes possible, as it seems feasible, 

 viewed from the imdications named, to turn about and utilize the simple 

 elements and compounds and build from them the more complex compounds 

 as found in plants and animals, it Avill be easily seen and understood how the 

 life forces of the cell operate. Although there are many streams to span, 

 it does seem that there is sufficient evidence now at hand to trace the path 

 most likelv to he followed in the future in the search of the interpretations 

 of life. 



We shall now try to show how the micro-organism furnishes an excellent 

 illustration of the way it can utilize and build up into the living substances of 

 the cell these simpler compounds which we find in the last step of the de- 

 gradation of the proteins and carbo-hydrates. 



Micro-organisms are not alike, it is granted, in their requirements. Uni- 

 forjnity is found only after such rec^uirements become a part of the cell 

 substance, the protoplasm itself. Even then, they may -differ sufficiently 

 to give individuality. In reality, micro-organisms are found which can 

 utilize the free nitrogen of the air, as discovered by Hellriegel in 1886, using 

 it in their own metabolism, or furnishing it to a host upon which they may 

 live. Again, there are those micro-organisms which use the free nitrogen 

 of the air without any relation to host, however, as has been shown by Wino- 

 gradsky (1893), and Beyerinck (1901). Still there are micro-organisms 

 that will oxidize nitrogen in the form of organic matter or ammonia to 

 nitrites or to nitrates; others reduce nitrites and nitrates to ammonia, and 

 free nitrogen. Still again, there are those which can assimilate carbon-dioxide 

 without possessing any chlorophyll. Along with these substances, mineral 

 ingredients become involved and probably are a part of all life's reactions. 

 Thus, we see the life of a micro-organism is simple; it may live upon the 

 elements of the earth and the air, yet, out of them are constructed the most 

 complex molecular bodies known to man. Their bodies are veritable labora- 

 tories of synthetic and analytic chemistry and physics. 

 : Assuming that life began in the sea, and that this life is dependent upon 

 a weak solution of the mineral constituents of the earth as found in the 

 water, then it is easily understood how that first sea life can be simulated 

 in micro-organisms. Lohmann makes the enumeration of microscopic 

 sea life in one cubic meter of sea water (off the coast of Syracuse, where the 

 sea is regarded as poor in these forms), to consist of: 2,082,740 protophyta; 

 325,510 protozoa; 17,415 metazoa; 785,000,000 bacteria. Johnston, who 

 notes the above, says: ''Assuming the composition of the plankton, such 

 as represented by Lohman's tables and regarding the total surface of all 

 planktonic organisms as equal to 1,000, he finds that the surface is shared 

 in the following manner: Protozoa, 29; metazoa, 148; bacteria, 400; pro- 

 tophyta, 423, and it would appear from these figures that the protophyta 

 (the diatomes and lower algae) play a more important part in the production 

 of the dissolved foodstuffs than any other group of organisms in the sea. 

 It is true that the total effect of Ijacteria would appear to be almost as great 

 as that of the protophyta, and we shall see that the general effect of the 

 metabolism of the bacteria is to convert all carbon compounds into carbon- 

 dioxide, and all nitrogen compounds into nitric acid or even free nitrogen. 

 It is only the protophyta among the plankton which can utilize the carbon- 

 dioxide and nitric acid compounds, and so we see that upon these rest the 



