plete series of illustrative specimens in all the departments of natural history for educational museums. The writer had repeatedly seen and admired collections of specimens from this establishment in colleges and other institutions, but it was only recently that he was induced to visit the former itself. It greatly exceeded his expectations, and surprised him by its extent as well as delighted him from the excellence and beauty of its collections. Many buildings were stored with admirably mounted and well-preserved vertebrates, snowy-white skeletons, a multitude of invertebrates, excellent models, fine collections of minerals, and characteristic series of rocks and fossils. Even in the great capitals of Europe nowhere did the writer see so great and excellent a stock from which to furnish museums; and it is in grateful appreciation of the able and zealous services of Professor Ward, in the interest of natural history, that the writer takes this opportunity of recommending his establishment to those who desire to obtain collections. In conclusion, to exemplify how much may be taught of whole groups or orders from a few specimens, the writer presents the following instance: He had in his possession a fragment of red coral, the material so much used for ornament. Notwithstanding much explanation, persons ordinarily appeared to him to be incredulous as to its animal nature. In viewing Professor Ward's collections, he espied among thousands of actual specimens a pair of beautiful models of the red coral, one representing the object of natural size covered with the soft flesh and exhibiting the tiny polyps; the other representing a magnified view, exhibiting a fragment of a stem with three polyps. These were purchased for one dollar each, and are now placed together with the natural coral fragment, and not only tell the whole story of the animal at a glance, but tell that of the whole order to which it belongs. Many such examples might be related, but one is enough.
It is this careful attention of Professor Ward to the scientific and educational import of his collections which has given his natural history establishment its high appreciation among the naturalists and the science teachers of our country.
| THE FORCE BEHIND NATURE. |
By WILLIAM B. CARPENTER, M. D., F. R. S.
SOME thirty years ago, I enjoyed opportunities of discussing with John Stuart Mill (whose younger brother had been for twelve months an inmate of my house) many questions of philosophy in which we both felt the deepest interest. Among these was the Doctrine of Causation set forth in his recently published "System of Logic": "We may define the cause of a phenomenon to be the ante-
