/ 
THE MICROSCOPE. 35 
empty Acanthocystis’ sac, had accomplished a part of its internal 
changes, but an awkward movement displaced the cover-glass and 
ruined all. 
Did that unhappy rhizopod in an absent-minded moment take 
in an egg, and did that egg eventually take in the rhizopod? Was 
the development of the egg so far advanced that the rotifer was 
hatched before it could be digested? Why was it? How was it? 
Oh, “I want to know, you know!” ; 
GLEANINGS FROM THE JOURNAL OF THE ROYAL 
MICROSCOPICAL SOCIETY FOR DECEMBER. 
Cah] STOWELL. 
THE REVOLVER MICROSCOPE AND A DEVICE FOR EXCHANG- 
ING OBJECTIVES.—These two objects are mentioned together for 
this simple reason, that Mr. E. H. Griffith, of Fairport, N. Y., is 
really entitled to the credit of inventing them. The revolver micro- 
scope consists of a circular stage, which can be rotated on its centre 
and also moved backwards and forwards. The stage, having the: 
pillar of the microscope for its centre, is capable of hoiding twelve 
_slides, each slide having three mounts upon it. The stage is first 
placed so that one of the mounts’on a slide is in focus and then 
simple rotation will bring the others successively in view. This is 
followed by either a forward or backward motion until the second 
mount on a slide is in focus when the instrument is manipulated as 
before. It is essentially an exhibition microscope. A number of 
years ago Mr. Griffith invented practically the same thing and he 
submitted his drawings toseveral parties, among them, I believe, was 
Mr. Gundlach who spoke quite highly of the invention but doubted 
whether he could make it a paying investment. The device for ex- ” 
changing objectives, given by Mr. J. Matthews, is on the principal 
of the cone. An adapter in the form of a hollow cone is screwed 
into the ordinary nose-piece, with another piece screwing on the ob- 
jective and coned down exactly to fit inside the first. The only 
action required then is to push the one into the other, and as they 
fit accurately there is quite sufficient adherence to keep the objec- 
tive in its place. Mr. Nelson declares this “to be the best fitting in 
the world,” and he would be glad to see “the whole system of 
screws Swept away and the cone substituted.” I remember dis- 
