1877.] Microscopy. 258 
three numbers of the Möller Probe Platte, with the new Tolles object- 
ives, the president states that further experience, and intercourse with 
experts in this special branch of work, has rendered such resolution so 
simple and easy as to cause wonder how it ever appeared difficult; and 
he adds the following very interesting remarks on apparatus and test 
objects : — P 
“In justice to Mr. Tolles it should be stated that the fault did not lie 
with the objective, but rather in our own inexperience, for, in proper hands, 
by its means, the No. 20, or Amphipleura pellucida was immediately 
resolved, after having procured the finest definition of the two preceding 
ones. While what I now say relates particularly to the jth, which 
has accomplished most satisfactorily all that was claimed for it, I cannot 
pass over in silence our new 3th immersion, by the same maker. With 
this objective I have by lamp light frequently resolved the last three 
diatoms on our balsam plate, which has been pronounced a more than 
ordinarily difficult one, with an ease and clearness of definition that is 
wonderful, and far surpasses anything I have before had an opportunity 
of witnessing. Not only does this glass possess in a superior degree 
the qualities heretofore claimed only for those having the highest angu- 
lar aperture, but such is its ample working distance and great penetra- 
tion, that it answers admirably for investigations upon animal and vege- 
table tissues, where those attributes are so necessary. 
“In speaking as I do with regard to resolving difficult diatoms, I would 
not have you think that I attach more importance to this matter than it 
really deserves, nor would I for a moment propose it as an end for any- 
thing more than to exercise the student in the manipulation of the 
microscope. In fact, as problems in mathematics teach the use of 
figures and quantities while they improve the mental faculties, so this 
resolution of diatoms, which has been so much decried as being a sad 
waste of time and energy, gives to the manipulator a skill in the use of 
his instrument without which no success can be obtained. If our effort 
were to end after having resolved a few diatoms, I should say our society 
was anything but a success, and although it might have afforded enter- 
tainment to its members for the last five years, it had failed to produce 
any good or lasting effect. To know how to use the microscope with 
skill is one thing, but to know what you see with it is another and a 
far more difficult subject ; but it is also one which we have by no means 
Completely neglected. That we have a realizing sense of the impor- 
tance of this branch, and that our progress has not been entirely in the 
way of material prosperity, I would present as an evidence the recent for- 
mation of a class in microscopy, under the instruction of our librarian, 
Mr. X. yY. Clark, which, I consider would have been an impossibility a 
few years ago, when so many of our members were interested in the 
microscope as a novelty, and, perhaps, without speaking offensively, more 
as a toy than as an instrument with which to acquire real knowledge and 
instruction.” 
