The

were counted dead in one place on the snow near the tunnel. little fellows were unable to get back to their boxes in the city and so perished from the cold.-SAMUEL LOCKWOOD.

PECULIAR COLORATION IN FISHES.- A short time since while examining a number of alcoholic specimens of Cyprinoids from Ogden, Utah, collected by Mr. J. A. Allen last September for the Museum of Comparative Zoology, I noticed a species of Richardsonius distinguished by a bright vermilion spot on the abdomen. The size of the spot varied in different individuals; in some it was quite small, in others it extended from the base of the pectoral fin to the anal opening. Calling Mr. Allen's attention to this fact he informed me, greatly to my surprise, that this color was not present in the living fish when he caught them, but appeared after the fish had been in alcohol a short time. A dissection of one of these fishes showed me that the color was deposited in the areolar layer or derm, and was therefore a true pigmentary color. The only explanation I can offer to account for this peculiar appearance of color is this:-it is well known that during the breeding season fishes frequently take on the most brilliant colors, which disappear when that season is past. Is it not therefore probable that this color may have been one, at least, of the colors assumed by the fish during the reproductive period, and that the alcohol served in some way to bring out the color thus abnormally.

Whatever may have been the cause, the fact that color can so appear in fishes will serve as a caution to ichthyologists when describing species from alcoholic specimens alone, lest they confound abnormal or seasonal colors with those that are permanent.

If any of your readers have observed a similar peculiarity in any other species of fish, I should be glad to learn of it through the pages of your magazine.-RICHARD BLISS, JR.

DURATION OF LIFE OF THE DANUS ARCHIPPUS.- About the middle of last September I found my first larva (i. e. the first I ever happened to see though the fly is common even hereabout) and took it home to feed. I afterwards found more, having finally eight pupas, dating from 1st to 13th October, half of which I gave away; of the balance two came out males, but imperfect, the third was a female and I kept it in an empty wardian case hoping the fourth might be a male. I cannot give the date of its appearance but it was about the 18th, and at the end of a week it was

still alive and trying to suck a bit of apple paring. I then offered it some sugar and water on which it fed greedily, but the solution being too strong stuck to its feet and in struggling it lost two of them. On the 30th the last fly came out a female, and then I determined to try how long I could keep her, making my sweetened water very weak. The first mentioned died on the 15th November, and the last on the 10th December being then forty days old, and I think might have lived longer but that in the mean time I had filled up my case with plants and as she persisted in keeping near the glass her wings were continually drenched by the moisture collected on it.-LOUIS MITCHELL, Norwich.

AMERICAN LEECHES.-Our fresh water leeches, neglected for so long, have at length received attention from Prof. Verrill, who contributes an illustrated article on them to the "American Journal of Science" for February. About twenty-five species are enumerated, most of them being new to science, one species (Cystobranchus viridus Verrill) lives in both fresh and salt water. Most of our common leeches belong to Clepsine, and are found under submerged sticks, etc. and occasionally on the under side of turtles, but they seldom, if ever suck blood. They feed upon insect larvæ, small worms, etc.

GEOLOGY.

A NEW CAVE IN BERKS COUNTY, PENNSYLVANIA, was discovered sometime last November and was explored to some extent in February 1872. The above cave is now explored to the length of about five hundred feet and in width nearly three hundred feet in several apartments composed of limestone and silicious rock. The stalactites and stalagmites are of a beautiful nature, some stalactites are nearly pure silica, some twelve to fourteen inches in length and one and one-half inches in thickness, and in one apartment all quartz crystals, some purple, are as near Amethyst as can be. I intend to explore the whole and expect to find a "bone care below, as the present floor, I am sure, at one time dropped down and is now from twenty to twenty-five feet in depth. I expect to find an entrance to the lower bottom. The temperature of the cave is from sixty to sixty-five degrees F. in some apartments. I think the stalactites are purer and finer than in the Mammoth Cave of Kentucky. The above cave is now

leased by Samuel Kohler about three miles from the village of Kutztown, who intends to have ready accommodations for visitors and explorers during this April.-H. W. HOLLENBUSH. Reading, Pennsylvania.

MICROSCOPY.

AN IMPROVED MODE OF OBSERVING CAPILLARY CIRCULATION. As I have never seen in print the following method of exhibiting the circulation of the blood in the frog. I send it hoping that it may enable some one interested in such studies to demonstrate the distribution and influence of the nerves upon the capillary vessels and circulation. I have, for over twenty years, been aware of the peculiar manipulation presently to be described; where I first obtained the knowledge, or how, I cannot state. I have made the facts known to a great many microscopists, and have not, as yet, met any one who previously knew it. If we grasp a frog in the hand and plunge it in water about as warm as can be conveniently borne, say about 120', though I have never measured this, judging simply from the apparent warmth to the hand, we shall find that, in a few moments, the frog will become perfectly rigid; it may now be removed and laid upon a plate for dissection. Carefully opening and stretching the parts by pulling upon the fore limbs gently, or even cutting the bones if necessary, the heart may be displayed, showing the contraction and expansion beautifully; and if now the animal is placed in warm water, the lungs will immediately float out, and by a suitably contrived stage, the circulation may be examined. It is better, however, not to do this but to draw out gently the large intestine by means of blunt forceps, and then spreading the mesentery on the glass of the frog plate (I find it convenient to use a large one with an elevated glass, instead of one in the same plane, on which to spread the mesentery) we can observe the capillary circulation very nicely with aor inch objective, by dropping a bit of thin glass over the place or with a higher power "immersion." Of course the parts opened must be kept moist and covered with a cloth, and a few drops of tepid water added from time to time. If the experiment has been properly conducted, the animal will remain perfectly quiet and the circulation will continue for hours; I cannot say how long, for I have never known it to cease until long after I had finished all the exhibition I have ever had occasion to make.

If the frog is a large one, the mesentery can be spread out so as to afford the most magnificent exhibition of capillary circulation, with a distinctness, and under an amplification which will excite the greatest admiration and astonishment in any one who has only seen it hitherto in the web, or the tongue.

The objectives of a high power ought to be more tapering at the end than our American makers usually furnish them. In this respect, some of the foreign objectives are superior. It would be very little more trouble to make the higher powers at the object end but little larger than the front lens, and thus infinitely more convenient for work than with the large flat surface which most of them now present. In fact, with a or American objective, as ordinarily made, it would be impossible to approach sufficiently near to the mesentery to focus on the smaller capillaries without striking some of the larger blood vessels. If nothing more could be done, the front set at least might be mounted in a little projecting tip or nose, and if those who are ordering objectives will insist upon this, I doubt not the opticians will do their part.—II. L. SMITH.

In the January number

THE NEW ERECTING ARRANGEMENT.of this Journal, and also in the Monthly Microscopical Journal of the same date, Dr. Ward describes A new erecting arrange

ment especially designed for use with Binocular Microscopes." The arrangement proposed by Dr. Ward will undoubtedly work as he proposes, but cui bono? It is an axiom in microscopy, as well as in other pursuits, that the simplest means of accomplishing an end is the best. Dr. Ward's arrangement is complicated and troublesome, and unless all the lenses are well made and carefully centred, definition will be injured. Dr. Ward is correct in his observation that the "erectors usually furnished [italics are mine] are not good and the use, otherwise satisfactory, of a good objective as an erector has not yet afforded the advantage of binocular vision." The first clause is correct because "the erectors usually furnished" reverse, counteract or destroy all the corrections which the opticians have taken so much pains to introduce into the objectives. The second clause refers to binocular vision. This has been completely accomplished by Tolles' binocular eyepiece which has been in use and before the public more than six years. Without any change from, or addition to, its regular construction or use, it gives an image erect, binocular and stereo

scopic with any objective, from a four-inch to a inch; and of course it may be used for dissecting by transmitted or reflected light with any objective having "working distance" enough for manipulation- certainly with a half-inch. The only objection, if it is one, against the instrument for this use, is that the "power," the amplification, is necessarily higher than with other binoculars. But where a very low power is wanted I believe a pair of spectacles set with magnifying periscopic lenses will prove to be better than any binocular dissecting microscope yet devised. But the objection to the "usual erector" for monocular instruments remains. This was remedied by Tolles years ago; so long ago that he has forgotten when. He made erectors that did not disturb any of the corrections of the objective, but preserved them and gave as good effects as were obtained without an erector.

When will American microscopists learn what has been done in instruments made in their own country, by their own artists? C. S.

NOTE ON THE ABOVE REMARKS. - It can hardly be necessary to state that Tolles' binocular eye-piece, with which the writer has sometimes worked, was ignored in the paper referred to, simply because there was no occasion to mention it, it being no novelty but an article whose properties, have been perfectly familiar to American (and foreign) microscopists for years. It is only fair to add that the new arrangement, which can be added to any microscope at a cost of two or three dollars, has been used for months by several microscopists who consider it extremely simple and convenient.

That an erector (or anything else) however perfect, can be added to the objective and ocular and give "as good" optical effects as would be obtained without the additional refracting and dispersing surfaces, is much disputed and surely cannot be considered a conceded point at the present time.

If Mr. Tolles is prepared to supply the market with erectors radically superior to those generally used, microscopists will doubtless learn the fact when it is announced, as I do not find it now, in the catalogue of the Boston Optical Works or in their advertisements in the NATURALIST and other journals.-R. H. W.

OBLIQUE ILLUMINATION.- A new contrivance, for obtaining oblique transparent illumination with high powers and black