PROCEEDINGS OF THE SOCIETY. 
437 
been considered, and found to be very much more convenient where it 
was than if put under the stage, and it did not stop the rotation of the 
stage for any practical purpose, it being impossible to give the stage a 
complete rotation. Putting it round on the other side would certainly 
be no improvement, and he appealed to practical men as to how they 
would like to have to turn round to the other side of the instrument to 
get at it. On the points raised he would therefore say that his judges 
should be the people who used that form, and not those who merely 
theorized about it. 
The President suggested that Mr. Mayall had not spoken of the 
instrument which Mr. Watson exhibited, but merely as to the principles 
of the construction. 
Mr. Watson said that was just his point, and he maintained that it 
was quite possible to make a Microscope on those principles which 
should stand the test of practical use. 
Dr. Dallinger said it appeared to him that when an instrument of 
that or any kind was brought before them, and their opinion was invited, 
remarks made could not be called criticism if they were not to speak 
honestly of what they felt to be its merits or demerits, as the case 
might be. Mr. Mayall, their Secretary, had, on his part, a very exten- 
sive knowledge of the JViicroscopes which had been produced by the 
makers of the world. Mr. Nelson also, on his part, had a practical 
acquaintance both with the construction and the working of the instru- 
ment such as few other persons had the opportunity of possessing. He 
might also add that his own laboratory contained instruments by every 
maker of any reputation here or elsewhere, and he felt bound to say 
that this form of fine-adjustment was not satisfactory ; indeed, for use 
with the highest powers it was most unsatisfactory. When they 
had a thread so fine as the 1/100 in., and placed upon it the whole 
weight of the body, the ultimate result could hardly be otherwise 
than as he had found it. When, as a defence, it was said that an 
arrangement which they had before them “ did not interfere with rota- 
tion of the stage,” it seemed as if it was time to inquire what was meant 
by rotation. Those who were engaged in special investigations knew 
quite well what they wanted, and the microscopist so employsd knew 
that he wanted to completely rotate, if need arose, the stage of the 
instrument he was using. His own feeling was that, when a Microscope 
of that kind was brought before them, there were only two courses open 
to them — either absolute silence, or absolute honesty, in the matter of 
criticism. 
Mr. Grenfell exhibited a photograph, taken by Mr. Nelson, of a small 
organism found a short time ago, the nature of which he had been as yet 
unable to determine, some of the best zoologists and botanists to whom 
he had shown it being unable to say whether it was vegetable or animal 
in its nature. The whole of the details were brought out in such a way 
as to afford a striking instance of the value of photography for such 
purposes. He also wished to mention that at the present time in the 
Botanical Gardens (and, he also believed, in the boating-pond, Regent’s 
Park) there were considerable numbers of a free-swimming infusorian 
known as Tintinnus , formerly described by Claparede. It was remarkable 
1891. 2 H 
