MICHIGAN ACADEMY OF SCIENCE. H 



and other factors, can, little by little, alter the molecular complexes of the 

 cell and these, in turn, change its structural features, it follows that unicellular 

 organisms may, within limitations, become so varied as to produce new 

 variations, new species, and perhaps, new classes. Eigenmann, in his study 

 of adaptation, has been able to follow changes in fishes which would lead him 

 to l)elieve that the salt water fish may become a fresh-water fish, and that 

 fresh-water fish may adapt themselves even to salt water conditions, and 

 that fish in caves may be influenced by the absence of light to such an extent 

 as to alter their visual organs. To do this, much time is required. 

 Unicellular life responds quickly to its environmental conditions; only a 

 a few generations are required to produce striking results. Nitrogen-gather- 

 ing bacteria appear in one form in some artificial media, and in another in 

 the nodule itself. The tubercle bacillus exists in the form of typus humanus 

 in man, typus bovinus in cattle, typus avius in fowls, with all forms be- 

 tween, according to Fibiger, Bang, and others. The micro-organism of 

 glanders loses its virulence in two or three generations when grown in artificial 

 media, but if passed through an animal frequently, its virulence is maintained. 

 A chromogen may lose its pigment completely in one generation, but 

 may recover it in another. If we consider the micro-organisms of the 

 sea, we can understand how they can, little by little, adapt themselves 

 from salt to fresh conditions and to different densities of brine. There are 

 those organisms which are easily influenced by salt, and those which grow- 

 readily in a twenty per cent solution. In the sea, too, there may be found 

 those which find themselves in the bodies of higher plants or animals, and, 

 after a time, may find it possible to produce pathological conditions; they may 

 escape from the plant or animal, find themselves stranded under entirely new 

 conditions, thus losing all of their former power to produce pathogenic effects. 

 It is not stretching the imagination too much to see the sea micro-organisms 

 stranded in bogs, where they soon adapt themselves to their surroundings, 

 or they may even accommodate themselves to droughts. Briefly, we can see 

 micro-organisms moving landward, seaward, becoming pathogens, chromogens, 

 photogens, zymogens, and can see them also moving in an opposite direction. 

 There is almost sufficient evidence to establish such a view as a fact, and yet, 

 it would not be safe at the present time to accept such a general statement. 

 The many individual cases of change and variation, of adaptation or adjust- 

 ment among micro-organisms without any established limitations must im- 

 press every investigator of the great possibilities open for more extensive, 

 as well as intensive, work along these lines. 



We are disposed to believe that functioning is gradually adjustable within 

 the limits placed by our natural environments, and that variations in morphol- 

 ogy of micro-organisms is a result of variation in functioning. If natural 

 processes are finite, then -development becomes finite; if infinite, then de- 

 velopment })ecomes infinite; whether finite or infinite, is now beyond the 

 finite mind. 



It is, therefore, significant that classifications upon which we are dependent 

 are exceedingly superficial, but, perhaps the best available at the present 

 time. In l^acteriology, physiological classification has progressed to some 

 extent, but it must be exceedingly limited, because of ignorance. When 

 it becomes possible to deal wdth the molecular complexes of the body, and 

 the many physical forces involved then will appear a more wholesome classi- 

 fication — one that is more stable and better unified. 



Man, as a rule, is not content to believe that he represents the chmax of 

 possible living forms; he likes to think of the indestructibility of matter, 



