come to the fore, is subject to the same restraints. 

 It gets around the difficulties of resolution not by 

 an improvement in the lens so much as in utilizing 

 an improved kind or quality of light. Its capacity 

 for magnification is no greater than its predeces- 

 sors', but its interpretations are more profound. 

 Notwithstanding that it reveals a light-effect 

 rather than an actual image, one reads by the help 

 of its rays messages from the microcosm, unde- 

 cipherable by any other means. 



Without question, lenses of greater resolution 

 than at present prevail are much to be desired. Yet 

 the fact remains that however much we resolve or 

 magnify, however far we penetrate these myste- 

 rious microcosmic labyrinths, there will always be 

 still further regions remaining to be explored, and 

 even beyond these will lie others without end. 

 None the less, for the ordinary worker, modern 

 lenses meet most requirements. Indeed, except 

 when pursuing a very special line of research, the 

 naturalist employs in the greater part of his work 

 relatively rather low powers. 



Now, as I have indicated, we have in the oil- 

 immersion lens a tool well worthy of our present 

 investigation of diatom structure. The oil-im- 



[125] 



