MICHIGAN ACADEMY OF SCIENCE. 9 



forces as revealed by chemical technique. Osmosis is a constant physical 

 factor to deal with in the study of micro-organisms. Heat and light 

 are essential factors. The tropisms have interested and annoyed students 

 of unicellular forins. Various forms of electrical energy are assuming an 

 important role and will, doubtless, in the future assist much in many of the 

 interpretations of vital forces. In other words, all those physical forces 

 which are connected, in any sense, with life's processes will, sooner or later, 

 have to be considered in connection with the various changes taking place 

 in the life of the cell or in all changes that are wrought by life's processes. 

 Looking at the origin of life from the standpoint of the physicist, Arrhenius 

 has conceived matter so finely divided and the surfaces so greatly increased 

 by this division, that the power of light would be sufficiently great to project 

 such matter from one planet through space to another planet, mathematically 

 speaking. He even goes further and believes it possible to have micro- 

 organisms of the smallest types convey life from one planet to another. 

 In other words, 



"From planet to planet the life-germ flies, 

 To cpicken the world that retains it." 



It is not incredible to imagine that micro-organisms can be so small as to 

 yield to removal by the power of light, for it is well known that micro- 

 organisms vary greatly in size and some are sd small as to tax the capacity 

 of the best microscopes. Ultra-microscopic forms have now entered the 

 field, and they are largely known by the analogy of their actions to those 

 of micro-organisms well established. These ultra-microscopic forms are 

 usually filterable. This would indicate that their size is small. I speak of 

 such organisms as those which cause yellow fever, horse sickness in South 

 Africa, cattle plague, and others. While Arrhenius conceives matter 

 mechanically divided so as to respond to the energy of light, in the case of 

 micro-organisms he assumes that there are forms so small as to correspond 

 in size with the possible physical divisions. By his views, however. 

 Arrhenius gets no nearer solution of the origin of life, even if he attempts 

 to transfer life's generation from planet to planet, for he must, eventually, 

 become tired in chasing the bag of gold under the rainbow. 



We must now leave the molecular consideration of the cell, in part, and 

 undertake for a time to study the cytology of the micro-organisms as 'iewed 

 from its structural standpoint. This transition can be best accomplished 

 in the words of Wilson, who says " Precisely as the various organs and tissues 

 are the seat of special activities leading to the formation and characteristic 

 transformation of specific substances — as for instance, hemoglobin is charac- 

 teristic of the red corpuscles, the chlorophyll of the assimilating tissues of 

 the plant — so in the cell, the various morphological regions are areas of specific 

 chemical activities and are characterized by the presence of corresponding 

 substances. The morphological differentiation of cell-organs is, therefore, 

 in a way, the visible expression of underlying chemical specialization, and 

 these are, in the last analysis, reducible to divisions of metabolic action." 

 In other words, there appears to be a direct relation existing between the 

 chemical, physical and structural features of the cell. 



The nutrition of unicellular organisms leads to many anomalies which 



will help us to understand the direct bearing of nutrition or metabolism 



upon its structure. In the study of micro-organisms, descriptions of 



morphological features must be based upon the nutrition furnished, otherwise, 



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