26 THE CANADIAN NATURALIST. [March 



a i in. or a i, or a i (although wonderful for excellence and defini- 

 tion in their way) which would come up to the analytical standard 

 of these high powers. 



Finally, I may say that I have never seen any French combina- 

 tions above ^ in. worth much. French opticians produce high 

 powers but a good English quarter will surpass them altogether. 

 Mere amplification is of no benefit in the microscope without 

 corresponding definition. I entertain also a decided prejudice 

 against a " thin skinned " glass. That is, one whose corrections 

 require the utmost nicety for the refraction of glass covers. In 

 my experience I have not found these the best glasses, and all 

 other things being equal I would reject a glass which was too 

 particular. Perhaps the class of work upon which I have been 

 engaged (crystals and tissues in fluid) has given me a strong 

 bias, but it is one which becomes strengthened by time, and which 

 the following incident will illustrate. Having a good Ross ^ 

 and 6, I wrote to Smith & Beck asking them to make for me a 

 student's ^, corrected to go through an ordinary round test tube. 

 They sent me a glass so corrected, for which they charged 

 £2 15s., one half the price of Ross' quarter with the adjustments. 

 I found it in every respect an excellent power. It would go 

 through the back of the slide and show the marking's on a pleuro- 

 sigma hippocampus or formosum, just as well as through the thin 

 glass. It would dip into a water cell, and for no purpose for 

 which I ever wanted a ^ in. did I find it deficient. Again, when 

 I acquired my old Ross' iV I had a fashionable new Ross' ^, 152 ° 

 ang-ular aperture in my possession. I found by frequent com- 

 parison that in the former glass I had not only a higher power 

 with better definition, but also a glass 7mich easier to u-ork, so I 

 parted with my fashionable friend and held on to my second 

 treasure. I would therefore counsel my friends who wish for 

 satisfactory high powers, not to follow the fashion, but to give the 

 preference to glasses of deep penetration and good definition, and 

 which work without very nice adjustment. 



In conclusion, I would take exception to the remarks of Mr. 

 Plumer at the close of an excellent article on this subject in the 

 Microscopic Journal, N.S., Vol. 4, page 167, viz., that his readers 

 " may reap by a short and royal road, all the benefits that it had 

 cost him years to acquire." I must confess my disbelief in this 

 " royal road." The royal road to microscopic or to all other 

 science is comprised in three words — work, work, work. More- 



