The Abbe Diffraction Theory. By J. W. Gordon. 357 



further function of a very mysterious kind ; and lest I should mis-state 

 it, I take the authoritative statement of this special function from 

 the translation of Naegeli and Schwendener's The Microscope in 

 Theory and Practice (p. 97). They say : — 



Fig. 67. 



" It is the diffraction of light in the object which produces the 

 image-forming rays of the fine structural details. These diffracted 

 rays produce well-defined diffraction or interference images in the 



