32 THE AMERICAN MONTHLY. l.l:mii:.rv. 



cxclaiiuiliitn mark had become detached and projected from the 

 edj^e. Mr. \\'rij;ht also sent pliotoniicro^raphs in support of 

 iiis statement. 



The chairman said he conKl not he sure, from ll)e cursory 

 examination lie had been ahle to make, that tlie exclamation mark 

 referred to in the letter was to he seen. 



Dr. C E. Heevor read a jiaper " On Methods of Staininji; 

 Medullatcil Nerve-Fibres." ilhistratinj; the subject by photo- 

 microjjraphs anil by a number of preparations exhibited under 

 microscojies in the room. 



The chairman said tiiey were much inilebted to Dr. Heevor for 

 his very intcrestinj; paper. It was of course a very good thing 

 to be able to dilVerentiate ncrve-fibrcs in the way described, but 

 it was a pity that they could not al.so so dilVerentiate 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. Hell read a paper by Dr. II. (i. PiHard " On the use of 

 Monochromatic Yellow Light in Photomicrography." 



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

 lar process with monochromatic light obtained by using screens 

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

 much prolonged the time necessarv for exposure. 



Mr. r. Ilaughton Gill said that he had used the copper light 

 filter for the same purpose, and hail foimd 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 

 ofV 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 PIBLICATIONS. 



The Microscope : Its Construction and Managcincnt. By 

 Dr. Henri Van Heurck. London, 1892. 

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

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

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

 theory of vision, photomicrograpiiy, and staining processes 

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

 microscopv, 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 <^I h di !i<«. 



