32 ORIGIN OF LOWEST ORGANISMS. 



mode of origin of these organisms. And yet by the 

 aid of the microscope, as I have elsewhere stated, 

 one can watch the appearance of almost motionless 

 specks, more or less uniformly diffused through a 

 motionless film of fluid, and can see them gradually 

 develop into moving Bacteria or into Torulce. So that, 

 where no visible germs previously existed, visible par- 

 ticles of living matter develop, and more or less rapidly 

 grow into distinct Bacteria. This may be best seen in 

 a drop of a fresh and very strong turnip infusion, which 

 has been filtered several times through the finest paper. 

 The drop, placed in a live-box, should be flattened 

 into a thin film by the application of the cover. 



Thus protected, evaporation takes place very 

 slowly, and with the live-box resting on one of 

 Strieker's hot-water plates, at a temperature of 85 to 

 90 F., and the latter upon the stage of the micro- 

 scope, one can easily select a portion of the field in 

 which either no particles or only a countable number 

 exist. If, therefore, around and between any mere 

 granules which may pre-exist, or in a clear space, one 

 gradually sees in the course of two or perhaps three 

 hours, a multitude of almost motionless specks (at first 

 about j-o-oVoV' m diameter) in positions where no such 

 specks previously existed ; and if these specks may 

 be seen gradually to increase in size and develop 

 into Bacteria and Tornlce, then, at all events, we are 

 able to say that these organisms can be developed 

 without pre-existing visible germs, and we have 



