Royal Microscopical Society. 175 



had the same result. After this I can hardly understand how Mr. 

 Hartnack, so skilful as he is in managing his own objectives, and so 

 familiar with the diatom in question, could have failed to show two 

 distinguished micrographers the very same details, unless we assume 

 that one person's eye is more apt than another to descry such 

 utterly minute features. 



Neither could I think otherwise in regard of Stodder's assertion 

 that the most distinguished German diatomologist, Dr. T. Eulen- 

 stein, failed in making out the same details with Hartnack's Nos. 

 10, 11, and 12 ; nay, with the strongest objectives of Koss, even 

 with the highest at present known, the wonderful -V^h of Powell 

 and Lealand. Such negative result does evidently contrast with 

 my own experience. If it might not be pleaded that more urgent 

 business perhaps prevented the great microscopist from giving his 

 precious time to the troublesome and not very easy task of examin- 

 ing so finely minute structures, which, though they do not consi- 

 derably advance our diatomological science, have certainly a great 

 importance for testing the relative value of our microscopes ; the 

 increasing power of which prompts us to even more dehcate re- 

 searches, by which the sphere of our knowledge is more and more 

 enlarged. 



On this subject I read in the Monthly Microscopical Journal 

 (Nov., 1870) that the illustrious Professor Huxley, at the meeting 

 of the E. M. S. (Oct. 12 that year), lamented the actual insufficiency 

 of our microscopes for histological researches, saying that " practically 

 the nature of the question just now is whether, in an organic tissue, 

 one could truly define a point not more than 50-^oo^th of an inch in 

 diameter ;" adding again, " Histologists, I fear, are at the end of 

 their work unless .... they could obtain microscopes which would 

 enable them to separate two points the 100,000th of an inch apart." 



To this I might confidently answer that what the illustrious 

 Professor thinks to be future has been attained already. In proof 

 that this is no vain presumption of mine, I adduce the following 

 reasoning : — Whoever takes any interest in the improvements which 

 are daily made in the microscope will surely have read of the various 

 articles and memoirs that, during these last three years particularly, 

 have been published in both the Quarterly and Monthly Micro- 

 scopical Journals by the most active and zealous microscopists. 

 Nobert's wonderful incisions upon a glass plate, disposed in thirty 

 graduated bands, till the last reaches 3 sVrth of a millimetre apart, 

 seemed at the beginning to baffle the highest powers of the most 

 perfect microscopes. Yet at the very beginning of 1867 I had the 

 satisfaction of resolving those minute striae to the yevj last. I know 

 that Mr. Nobert, after he heard that the microscope had met his 

 challenge, increased his divisions till he reached the TrVoth. I 

 have not had the opportunity of putting my microscope to this new 



