18 The Microscope. 



grade, and I have had some experience in this matter. The 

 workmanship of this student microscope is unexcelled by any- 

 thing made elsewhere and unequalled by any German instru- 

 ment I have ever seen. Yet this microscope is altogether 

 American ; and there are a hundred such in use by others than 

 'amateur collectors' within my microscopical horizon. . .If we 

 turn now to the highest class of microscopes, such as the expert 

 purchases for his own use, the best of German and French make 

 are but candle-sticks compared to the American or English. 



"After all everything doesn't depend on the microscope. The 

 brain behind it is an important factor. Already our best makers 

 give us instruments too good for the execrable microscopical 

 work done in some university and college laboratories. A large 

 part of it has no real educational value for the student, and 

 happy should he be if he escape the dogmatism of his demon- 

 strator, or see with positive clearness one preparation retaining 

 all the delicate morphological elements Nature puts in it." 



This is admirable doctrine preached in an incisive and admir- 

 able way. In the quotation I have taken no liberties with 

 the author's italics. The stand that he describes is evidently one 

 of Mr Zentmayer's superb instruments, probably the Histo- 

 logical. 



CAN MOUNTING MEDIA BE IMPROVED FOR HIGH 



POWERS BY INCREASING THE INDEX OF 



REFRACTION? 



J. D, BECK. 



IT has been the aim of the microscopist to increase the re- 

 fractive power of mounting media for Diatoms, bacteria, 

 biological and other specimens requiring a high amplification 

 and the best resolution. Whether better results are attainable 

 in this direction I am unable to say. All my Diatoms, slides 

 from J. D. Moller, et al., are mounted dry or in balsam ; I have 

 never tried Prof Smith's medium. If the increase in refraction 

 is an improvement, would it not be a desideratum to attain still 

 more satifactory results, which perhaps might be accomplished 

 by increasing the index of refraction of mounting media? The 

 desideratum is to see what exists, and to secure for that the most 

 favorable means, bearing in mind that we must not expect too 

 much from the best lenses under unfavorable conditions or cir- 



