Mourne, July i 1610. NOTES AND MEMORANDA. 49 
Micro-Photo-Lithography.— Dr. Duchenne, of Boulogne, the well- 
known advocate of Faradization in the treatment of diseases, lately 
presented to the French Academy of Medicine a series of photo- 
lithographs of nerve-sections. According to ‘ Nature’ he stated that he 
had obtained excellent results from sections of the great sympathetic 
nerve, the spinal ganglia, the spinal cord, and of the medulla oblongata 
when magnified from 8 to 500 times. The plan was suggested some 
years ago by Dr. Duchenne himself; but it was found that the photo- 
graphs obtained in the ordinary method were not persistent. He 
therefore fixed them on stone by a process he terms photo-autography, 
the details of which, however, he does not communicate. It is satis- 
factory to find him stating that the results of his experiment and 
photographs only confirm the substantial accuracy of the beautiful 
drawings made by Mr. Lockhart Clarke on the central parts of the 
nervous system, and especially upon the medulla oblongata. In his 
later experiments Dr. Duchenne has adopted Mr. Clarke’s mode of 
preparation with chromic acid and carmine. He states that certain 
micrographic details come out with wonderful clearness in the photo- 
graphs, and that by this means some important additions may be made 
to our knowledge. Thus he has ascertained that in the white substance 
of the medulla oblongata there are a large number of very small nerve 
tubules, 0"™:0033 diameter, mingled with others of average and of 
large diameter, 0™":01 to 0™™: 02 and °03. 
American Object-glasses—Mr. Wales’ new xsth inch.—The fol- 
lowing correspondence relating to Mr. Wales’ ,4,th lately made, and 
Mr. E. Bicknell’s and Dr. Higgins’ remarks thereon will, we doubt 
not, be of interest to Fellows of the Royal Microscopical Society. It 
is published in the ‘ American Naturalist’ for June :—A performance 
of a ,4,th objective made for me by Mr. Wiliam Wales, of this city, is 
of such a superior character that I have no doubt it will be of interest 
to many of your readers. With direct or central light in contradis- 
tinction to oblique, and with the diatom mounted not dry, but in 
balsam, the Pleurosigma angulatum is beautifully resolved; the three 
sets of lines being brought into view with great distinctness, and this 
with the No. 1 or A eye-piece. Amplification 210 diameters. With 
no equal power of Powell and Lealand’s of London, of Hartnack of 
Paris, of Tolles and Grunow of this country, or of Gundlach of Vienna, 
various objectives of each and all of which makers I have examined, 
have either I myself, or other microscopists of my acquaintance, been 
able to effect this. Another feat which I had recently the honour of 
exhibiting to several members of the “Bailey Microscopical Club” 
of this city was a resolution of the podura scale with its light central 
markings with this same ,4,th. The resolution of the striz on human 
muscular fibre by a 3-inch objective, also made by Mr. William Wales, 
of this city, again challenges our admiration.—J. J. Hicerns, M.D., 
23, Beekman Place, New York. 
[We referred this note to Mr. E. Bicknell, who kindly sends the 
following reply.—Eps. of ‘ American Naturalist.’ | 
Messrs. Epirors oF THE ‘ AMERICAN NATURALIST, —In answer to 
your question in regard to the above communication, I would say that 
VOL. Iv. _E 
