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PEOCEEDINGS OF SOCIETIES, 
Microscopical Society of San Francisco. 
The regular meetiDg of the San Francisco Microscopical Society 
was held on Thursday evening, May 18, as usual, with a good attend- 
ance of members present. 
Mr. Kinne read an interesting paper on a new variety of acarus 
found in the ulcerous root of the lemon and orange trees, and exhibited 
the living animal, with the same mounted, to show the various parts, 
after treatment with carbolic acid to render them transparent. Several 
important differences were noted from others of their kin, which the 
prepared specimens and an enlarged drawing on the black-board made 
quite plain. 
Mr. Hyde offered a plan to be observed in the selection and arrange- 
ment of objects for the annual reception, which, slightly modified, was 
adopted. 
The fourth annual reception of the San Francisco Microscopical 
Society was held in Mercantile Library Hall, on Thursday evening, 
May 25. 
The regular meeting of the San Francisco Microscopical Society 
was held on Thursday evening, June 1, President Ashburner in the 
chair. 
Mr. C. L. Peticolas, of Richmond, Va., sent the Society a finely 
mounted slide of fossil diatoms from that place. 
Mr. H. G. Hanks donated a slide mounted with diamond boron, 
which he had prepared in his laboratory. Mr. Hanks describes this 
very interesting substance as an element of which boracic acid is the 
teroxide. Like carbon, it assumes three allotropic forms, the amor- 
phous, the graplioidal, and the crystalline, or diamond boron. It is 
the hardest of all known substances, scratching even the diamond 
itself. 
Mr. J. Edwards Smith, of Ashtabula, Ohio, corresponding member, 
sent the following : — The Cincinnati ' Medical News ' for May, 1876, 
contains a description of two amplifiers by the Eev. J. H. 
Wythe, M.D. 
Dr. Wythe informs your Society that during the past two or three 
years he has made many experiments, resulting in the discovery of 
two amplifiers, both of which he describes — I quote Dr. Wythe's 
own words : " The second form of amplifier is better still, and con- 
sists of a double concave lens, having a virtual focus of about one and 
one-half inch, at the end of a tube about 6 inches long, at the other 
end of which is the ordinary negative eye-piece." 
I have in my possession exactly the amplifier above described, 
which was made for me by Mr. R. B. Tolles seven years ago, and it 
has been in almost daily use. My attention was first called to the 
amplifier from seeing an advertisement of it by Mr. Tolles, and it 
must have been some two years afterward that I sent to Mr. T. my 
