JOURNAL 



OF THE 



ROYAL MICROSCOPICAL SOCIETY. 



JUNE 1904. 



TRANSACTIONS OF THE SOCIETY. 



VI. — The Influence, of the Antipoint on the Microscopic Image 



shoivn Graphically. 



By Edward M. Nelson. 



CRead February 17th, 1904.) 



It was stated in the Journal* that if one of the minute spinous hairs 

 on the delicate membrane of a blow-fly's tongue were examined 

 on a bright ground, the image would present an unreal tenuity and 

 sharpness, whereas if the same hair were viewed with dark-ground 

 illumination, it would have a swollen 

 or thick appearance; also, that the 

 difference between the two images of 

 the same object was caused by anti- 

 points, and that the true image lay 

 between these two pictures ; a table 

 was also given showing the amount 

 to be added to the micrometric mea- 

 surement of an image on a bright 

 ground to bring it up to its true 

 value. 



Mr. Gordon has made a most 

 excellent drawing of these two 

 images (figs. 47 and 48); a careful 

 examination of them will bring the 

 importance of the antipoint effect 

 home to those microscopists who do 

 not care to wade through physical optics and dry mathematical 

 tormu se. These drawings have been most carefully compared 

 with the original, as seen in the Microscope, and were found to be 



Fig. 11 



Fig. 48. 



June 15th, 190J+ 



* Journal R.M.S., 1903, p. 579. 



U 



