THE VITAL PHENOMENA OF BACTERIA. 107 



that the process is carried on through the 

 utilization of formaldehyde. Owing to this 

 peculiar method of obtaining energy the pro- 

 cess is independent of light, indeed it is car- 

 ried on better in the dark. From this we may 

 recognize the fact that the assimilation of car- 

 bonic acid is a physiological property of all 

 protoplasm, and that the chlorophyl function 

 is an adaptation to life in the presence of light 

 which has developed out of simple initial stages. 

 In harmony with this view is Pringsheim's 

 theory that chlorophyl is only a physical de- 

 vice for protecting the assimilating cell-proto- 

 plasm against too strong sun-rays which would 

 eventually kill unshielded living matter. The 

 injurious action of light-rays has been empha- 

 sized by bacteriology. That all energy is 

 ultimately derived from the sun is a fact with 

 which the development of individual adapta- 

 tions has nothing to do ; in view of the vapor- 

 ous atmosphere that prevailed in early geologic 

 times, the first life upon the earth must have 

 existed in the absence of direct sunshine, and 

 only later could it have adapted itself to direct 

 sunbeams. A connected history of the evolu- 

 tion of living things does not favor the con- 

 clusion, which the early botanists could not 

 help drawing, that chlorophyl was the first 

 created of organic bodies. 



