making his establishment a medium of exchange between parties in different localities. For instance, A lives in Central New York; he has plenty of Menobranchus, and would exchange them for Menopoma from the Ohio River, or the gars and spoonbills of the Mississippi, of which B has more than he wants; while both these parties desire sharks, and skates, and pipe-fishes, and the large lamprey from the seacoast where C lives. To purchase and keep all these and many more such on hand involves an enormous expense and risk to a single individual; whereas, if, under certain conditions, Prof. Ward received good specimens of these forms, and stored them at the owner's risk as to fire, and expense as to alcohol, etc., then he could, at a fair commission, transfer them to those who desired them without the expenditure now incurred.
The arrangement could be made like that of the naturalists' agency for books in Salem, Massachusetts, and a periodical list of specimens and prices could be issued. The prices would serve as guides for either exchange or direct purchase.
Such a system of transfer would, it seems to us, not only enable new institutions to rapidly form type collections for class-room instruction, but also encourage them to collect large numbers of duplicates of the forms peculiar to their localities. In this way we should ascertain the extent of individual variation, the manner and rate of development and growth, and, by preparations made on the spot, the structure of the brains and other soft parts, which are seldom perfectly preserved in specimens sent in alcohol from a distance.
WHAT are the so-called chemical elements? Are they really elements, or only compounds of remarkable stability? It would be hard to find in physical science a question which has been oftener asked than this. It has furnished all sorts of investigators with abundant food for speculation. Men of the highest scientific ability have grappled with the problem, and left it still unsolved; others have constructed elaborate theories, which claimed to settle everything. Still the debate goes on. We cannot prove that the elements are truly what we call them, nor can we show beyond all doubt that they are compound in their nature. We may, however, weigh the opposing probabilities, and see which side of the question is the stronger. Whichever way the balance turns, the superstructure of chemistry will be but little affected. We know that all our recog-