SUPPLEMENT. 379 



when German pathologists were in the habit 'of using common 

 window glass to cover their mounts, and at that time the 

 extremely thin glass, now so easily obtainable, was unknown. 

 All this is now changed ; the widest angled lenses known giving 

 all desirable amplification, will admit the use of covers l-50th 

 of an inch thick, while covering glass measuring .003 can easily 

 be procured. 



A vast amount of work has been done with these k ' honest 

 and reliable working glasses," and, as I have before said, will 

 have to be done over again, and this revisory work is now in 

 progress. But while there is some excuse for the investigators 

 of the past, who used the best instruments then obtainable, 

 what shall we say of those of to-day who persistently refuse to 

 avail themselves of the wonderful progress the optician is able 

 to demonstrate in this centennial year ? 



I have advanced the idea that working pathologists were too 

 often content to work with poor tools. I made that remark in 

 good faith, and believe tnat it will be found to be trne. Never- 

 theless the pathologists of the past, or even of the present day r 

 are by no means wholly at fault, when we remember that the 

 entire corps .of observers to whom we are indebted for all that 

 has been taught through the aid of the microscope, were men 

 who were regularly engaged in the respective duties of their 

 several professions, and that most of them have tilled profes- 

 sional chairs in various institutions of learning. These men, in 

 studying the use of the microscope, each and every one of them 

 were compelled to dig and trench for themselves; the instru- 

 ment which to them was as all-important as the compass to the 

 navigator, was far, very far, from being as true and reliable a* 

 " the needle to the pole." Once launched on the unknown, but 

 to them, fascinating sea of scientific investigation, every spare 

 moment that could be snatched from their regular engagements 

 was devoted to its exploration. It was a tiny sea, within a 

 microcosm, replete with interest, and capable, as if by the touch 

 of the optician's wand, of boundless expansion I 



These self-abnegating, self-sacrificing men fully accomplished 

 their task. It was a labor of love, and the results they obtained 

 were given to the world without money and without price. 



