32 THE AMERICAN MONTHLY. [January. 



exclamation mark had become detached and projected from the 

 edge. Mr. Wright also sent photomicrographs in support ot 

 his statement. 



The chairman said he could not be sure, from the cursory, 

 examination he had been able to make, that the exclamation mark 

 referred to in the letter was to be seen. 



Dr. C. E. Beevor read a paper " On Methods of Staining 

 Medullated Nerve-Fibres," illustrating the subject by photo- 

 micrographs and by a number of preparations exhibited under 

 microscopes in the room. 



The cliairman said they were much indebted to Dr. Beevor for 

 his very interesting paper. It was of course a very good thing 

 to be able to differentiate nerve-fibres in the way described, but 

 it was a pity that they could not also so differentiate them as to 

 show from which part of the nervous system they came. If this 

 could be done, he need hardly say it would be of great value. 



Prof. Bell read a paper by Dr. H. G. Piffard " On the use of 

 Monochromatic Yellow Light in Photomicrography." 



Mr. T. Charters-White said that he had himself tried a simi- 

 lar process with monochromatic light obtained by using screens 

 and solution, but the chief difference he found was that it very 

 much prolonged the time necessary for exposure. 



Mr. T. Haughton Gill said that he had used the copper light 

 filter for the same purpose, and had found that by its aid any 

 good ordinary lens would give as good results as were otherwise 

 obtained by using an expensive apochromatic, because it filtered 

 oft' all the rays except those which were visually strong. He 

 had not found in the course of his work that the use of this light 

 prolonged the exposure ; that was to say, that with a magnifying 

 power of 300, and an exposure of ten minutes, he could, with 

 the isochromatic plates, get a good, strong, printing image. 



NEW PUBLICATIONS. 



7^/ie Microscope : Its Construction and Management. By 

 Dr. Henri Van Heurck. London, 1892. 

 Mr. Baxter of Sussex, England, has translated the 4th edition 

 of Van Pleurck's treatise, which, while containing elementary 

 matter, also covers the whole field of microscopy. Abbe's 

 theory of vision, photomicrography, and staining processes 

 receive special attention in this edition. As to the future of 

 microscopy, it is believed that but few further improvements will 

 be made in the microscope. The frontispiece consists of a por- 

 trait of the famous botanical professor and director of the 

 Antwerp Gardens. 



