280 THE AMERICAN MONTHLY [Sept. 



study, always under applicatiou of excess of water. The 

 pressure must be very gentle, especially when the spe- 

 cimen gets thin; the result now depends somewhat upon 

 the skilfulness of the operator. When the section is thin 

 enough, which must be controlled under the microscope, 

 it must be carefully cleaned in distilled water, and finally 

 mounted in Canada Balsam. — Dental Cosmos. 



EDITORIAL. 



Oliver ^Vendall Holmes, a Microscopists. — Forty-one 

 years ago, Dr. Holmes who was 85 years old on August 29. 

 1894, taught Dr. E. Cutter how to use the microscope with di- 

 rect illumination. He had an arrangement of his own, — a six- 

 inch black disc fastened to the tube and graduated so that turn- 

 ing the disc would act as a fine adjustment. Dr. Cutter says 

 that Dr. Holmes worked a good deal with the microscope in 

 those days and that the intellectual drill derived therefrom may 

 have been used in literature. Is not the technical use of the 

 microscope in college as good a discipline as the stud}^ of Greek? 

 Surely the cyclops of the Odessey would be better understood 

 by one who has studied a living cyclops taken from a hydrtmt 

 and shown under the microscope. 



Centrifugation — to separate sediment, is coming into gen- 

 eral use among European investigators. A number of instru- 

 ments are in use for the purpose. 



Photo Micrographs. — At the British Medical Convention, 

 Mr. Andrew Pringle made the following exhibits and explana- 

 tions. 



At schools of medicine and the like, where a large number of 

 students are engaged in studies which are only made possible 

 by the use of the microscope, it has been customary to cut a 

 large number of sections from a piece of tissue, and to examine 

 such sections, each under a diff"erent microscope, for the micro- 

 scope is an instrument which permits of only one observer at a 

 time. Now, no two sections can be identical, and more often 

 than not, critical points, upon a right appreciation of which the 

 subject-matter of a lecture may altogether depend, are absent i i 



