REPORT OF THE ANNUAL EXHIBITION OF THE BIOLOGICAL AND MICROSCOPICAL SECTION OF THE ACADEMY OF NATURAL SCIENCES OF PHILA

DELPHIA.

The committee appointed by the Biological and Microscopical Section of the Academy of Natural Sciences to report the principal features of a public microscopical exhibition, held in the hall of the Academy, April 5, 1883, offer the following report:

We have felt how difficult it is to hold in remembrance, even long enough to frame a report, such a large mass of miscellaneous objects and facts as have been presented to our notice. Only the desire to render the section an impartial, yet not useless report, gives us any encouragement to undertake the task.

The museum of the Academy was lighted on the evening of the meeting, and, as has been usual on former similar occasions, the entire building was nearly filled with deeply interested students and observers of the minute, but beautiful, things in both the inorganic and organic worlds. Even a careless observer could not fail to notice the deep interest-far removed from mere curiosity- which our citizens take in such exhibitions. Hundreds of thinking people are thus brought eye to eye with the demonstration, that what they call the invisible world is as vast and as beautiful, and may be rendered as clearly visible, as the known objects which they daily see around them, and they leave the hall of microscopical science with juster and wider views of the beautiful world in which they live.

The entomological section was the only section of the Academy which contributed to the interest of the meeting. Its display of brilliant and interesting insects arranged in cases, visible but not to be handled, was a prominent feature of the evening, and will prove of educational value to many.

Your committee would report a general advance in microscopy since our last exhibition.

One hundred and nine microscopes of all grades of excellence and variety of forms were on our tables. Of this number, Zentmayer's counted 50, Beck 29, Crouch 12, J. S. Cheyney 11, Queen & Co. 7, Bousch & Lomb 7, Seidel & Polk 6, Seitz 2, Nachet 2, Hartnack 2, Seward 1.

Several microscopes claiming to be first-class, made regardless of expense, and fitted for all kinds of work, were on exhibition. In this class of microscopes Zentmayer gave us the ideal. His Centennial stand has no rival. Its splendid finish, simplicity of parts, durability and perfection of motions place it in advance of all others on exhibition. In this class of work imperfection is inexcusable. Beck also exhibited two first-class stands of recent work, and these stands have some motions lacking in the Centennial form. Crouch had one stand on exhibit claimed as first-class. Its workmanship was good, but its great undescribable merit is the honorable one of not having adopted Zentmayer's patent for swinging the sub-stage.

Since our last public meeting a gratifying improvement is reported in workmanship among microscopes of less pretension than those already mentioned. These second-class instruments are the ones with which most work is done, and excellence here is of supreme importance. Beck exhibited a new stand showing excellent workmanship for so cheap an instrument. The "Lithogical," by the same maker, is ingeniously adapted to the examination of rock sections. Zentmayer's "Histeo logical" and improved "Army" stands maintain their perfect finish and motion.

Queen & Co. exhibited a new model "Acme" stand of greatly improved workmanship. The stage is of black glass, and the tube has the "broadgauge "

screw, also an adapter for the "society. screw. Their "College" microscope and "Amateur" show good work for a moderate price. Bousch & Lomb in all their microscope stands on exhibit, show their ability to do work which ranks among the best.

The microscopes shown by J. S. Cheyney had no pretension to fine finish, and could doubtfully be classed among instruments of precision. The style of work of every maker of microscopes is characteristic, and, like the style of authors in literature or science, soon become known to the expert. Instruments Instruments by other makers which were on the table and did so much for the entertainment of the evening, presented no new features, and have been noticed in earlier reports.

Beck and J. S. Cheyney each exhibited cameras adapted to microscopes for micro-photography by lamp-light. It is claimed that good results, with amateurs, can be secured in that way. The apparatus, however, contained nothing new, and the results gained (if a judgment may be based upon a number of pictures shown) indicate no recent advance in this kind of amateur photography. We accept it as better than nothing, but the eye instructed in detail is always disappointed.

J. S. Cheyney also exhibited a projection microscope, carrying a quadruple nose-piece, for photographic transparencies, polariscope, microscope and spectroscope, for projection. It is claimed that all these parts will swing into accurate centre, and can be instantly changed during a lecture. Your committee did not see the apparatus in action and therefore cannot more fully report.

On the subject of lenses, nothing not previously reported came to the notice of your committee.

The objects shown during the evening were numerous, and extremely varied, and many were exceedingly beautiful and

of great interest. We can report only the most interesting, or those not mentioned formerly. From the animal kingdom the list is large. Human lung, engorgement in active pneumonia; human lung with all the capillaries filled with blood, in phthysis; circulation of blood in tail of fish and in salamander; action of the heart in living salamander, and branchial circulation in one view; section of rat's lung, and lung of squirrel with capillaries filled with blood in situ, double stained. Human spinal cord; spinal cord of cat; section of cat's tongue; leg of gyrinus, showing hairs used as paddles; skin of frog, injected; human tooth; liver of rabbit; skin of sole of foot, showing sweat glands; intestine of cat, injected; Rotifera vulgaris; Lascunularia socialis; Dictyophora; a new rotifera without rotating organs. Many living infusoria; Bacilli anthrax in lung, sometimes found in Anthrax and therefore the cause of anthrau; micro-maggots in cheese, therefore the cause of cheese; Elytron of cupes capitata; tarsus of dityscus; foot of spider and of fly; parasite and ova of anodonta; head of mosquito; ant lion; brain of sheep; section of the human heart; section of hand in human foetus, four months old, double stained; section of a bot from stomach of horse; transverse section of gastric tubes, human, double stained; flea from mole and dog; spinarets and foot of spider. Many acquatic larvæ ; hooklets of wasps' wing; barbs of peacock's feather; elytra of diamond beetles; fresh water hyra; fresh water sponge; a series of 50 typical wools and hairs, commercial tests; eye of beetle, under a cobweb micrometer'; wings of various butterflies, etc.

From the vegetable kingdom we report only the following, although the list was large A series of 50 vegetable fibrescommercial tests; section of rubus; section of clematis; waterglands of nepenthes; fructification of several ferns; double

cle on Impressions, by W. R. Hall), it would seem but just and proper that they should give due credit to the source from which they obtained it.

AMALGAM FILLINGS.

Much has been said and written, pro and con, relating to amalgam as a filling material. We do not propose to further discuss the question with regard to its usefulness in saving teeth, or the advisability of employing it in many cases which the dentist is called upon to treat.

It is conceded by a vast majority of the very best men in the profession that there are cases in which its skilful and intelligent use gives more satisfaction than can be obtained with any other material yet known to dentistry. We simply wish to enter our protest against the careless and slovenly manner in which it is frequently used, even by some of our best manipulators of gold.

We have seen mouths containing gold fillings whose artistic contours, and beautiful finish indicated a high degree of manipulative skill in that direction; and in the same mouth, amalgam fillings with rough surface, imperfect and often overhanging edges (and the whole appearance of which was a disgrace to any dentist), all put in by the same operator, of whose ability as a dentist we have no better opinion than we have of the man who can make a good amalgam filling, but whose operations in gold are not of the best.

It has been often said by those gentlemen who contend for the exclusive use of gold, that the failure of that material to produce invariably good results is due to defective manipulation. If this is true in regard to gold, it is no less true with regard to the material under consideration, and we believe that as large a percentage of its failures is due to the careless man

the poorer the tooth-structure, and the more delicate the walls of the cavity (or, in the language of the New Departurists) "the more a tooth needs saving" the greater the care and skill required both in the preparation of the cavity and the introduction and finishing of the filling, in order to accomplish that end,—no matter of what material the filling may be composed.

Judging from the appearance of many fillings seen in the class of teeth just mentioned, it would seem that the operator has hardly deemed them worthy of any attention at all, and that he was evidently not a believer in the old adage, "what is worth doing at all is worth doing well."

A dentist's business success should depend, primarily, upon his ability to save teeth, and his reputation in this direction may as frequently be enhanced by the good results produced with amalgam in some badly decayed, broken down molar, as by his skill in the manipulation of gold. We are not a believer in the wholesale use of amalgam, but we do use it where, in our judgment, it is indicated and with the indulgence of our readers, will give the manner of using it which has given us the most satisfaction.

The cavity should be absolutely dry, and carefully and thoroughly prepared, in fact, when prepared it should be in as good condition as it would be if it were to receive a gold instead of an amalgam

filling. The filings should be well incorporated with just sufficient mercury to form a smooth, easy working mass; this is most quickly and thoroughly done in a small mortar. In introducing the amalgam into the cavity, small or moderately sized pieces should be used, and each piece carefully adapted to the walls of the cavity or incorporated with that which has preceded it, by tapping with properly shaped instruments as reccommended by Prof. Flagg.

Should there be an excess of mercury, it must be removed from time to time during the progress of the filling until finally, when the cavity is full, all excess should be removed with pledgets of cotton, or, what we think better, by the use of wafers of amalgam from which all the mercury possible has been squeezed by the use of the pliers and buckskin.

If the amalgam should be a quick setting variety, a fairly good finish may be obtained at the time of introduction, but we never feel satisfied until at a subsequent sitting, when the filling has become thoroughly hard, we have had an opportunity to give it a final polish. In doing this we never use a burnisher, for if there are delicate edges they would be liable to fracture.

With the lava strips, emery cloth, tape and fine pumice, or with some of the various polishing points for use with the dental engine, there is little difficulty in obtaining a beautiful surface, with the junction between the filling and cavityedge absolutely flush and perfect.

We are satisfied that very many of the failures of amalgam fillings would be averted by more careful attention to this last step of the operation. If any of our readers have never tried this method of using amalgam, we advise them to do so. They will be astonished at the neater and cleaner appearance of the mouth, to say nothing of the increased durability of the fillings.