Mackaiana, Bab., lays claim to be a species distinct from E. tetralix, Linn., from the midrib of the leaf and the sepals, together with the ovary, being glabrous.

The beautiful genus Erythraa affords a striking instance of the slender and unsatisfactory characters it is sometimes necessary to employ to distinguish nearly allied, though very distinct, species. In this genus Britain is peculiarly rich, and especially this neighbourhood, where all our native species grow wild. But what are the describable characters by which we can determine them? Only the relative length of the teeth of the calyx. Now this character is most doubtful and uncertain, and ought only to be relied on when all others fail; which we are bound to admit is the case in this instance; for although these species possess a peculiar habit and generally distinct appearance, it must be admitted that to the present time all have failed in discovering any tangible characters. When comparing, a few months ago, numerous specimens of this genus from this neighbourhood with plants in the Smithian Herbarium, at the Linnean Society, I was very much struck with the evident signs of labour Sir J. E. Smith had bestowed upon the genus, to discover permanent characters for the determination of the species. Babuglir, following Smith after a long interval of years, lays great stress upon the length of the calyx, which he states must be observed at the time the flower opens.

This character, conveying as it does rather an indefinite idea, appears most unsatisfactory, and quite insufficient to distinguish one species from another; and it is only when the plants are placed side by side that we see the difficulty in finding words to convey an adequate idea of the distinctions then so apparent, or how much more value is to be placed on the habit of the plants than on anything else.

From the variable nature of certain organs of vegetation, which in certain tribes are so readily acted upon by the influence of soil and climate, it is quite clear that we cannot

rely upon the same characters or set of characters for the determination of species in all cases. How then are we to proceed? We must look elsewhere; and thus we are compelled to seek for more permanent distinctions in habit or in the morphological characters of plants, a branch of the science much neglected, but one which will amply repay the scientific enquirer for the labour of his investigations; for only a casual acquaintance shows the unerring constancy of certain forms of growth, colour, or hue, in certain species, characters which they retain under all circumstances and in every state. For instance, what two plants can be more distinct than the Silene inflata and S. maritimi, already referred to? The upright mode of growth of the former, as compared with the repent habit and crowded state of the leaves in the latter, would sufficiently characterize the two plants at any time. Then again, in Echium vulgare, Linn., we find a most decided distinction in the lateral spikes of flowers, whereas in E. violaceum, Linn., its near ally, the spikes of flowers are to a great extent panicled. The erect and rigid frond of Polypodium calcareum, Sm., is quite sufficient to distinguish it from its more graceful congener P. Dryopteris, Linn., without even having recourse to the glandular scales of the former.

But, while we admit that great, very great, value must be placed on the habit of plants in describing the characters of nearly allied species, it cannot be denied that great care is requisite to guard against carrying this principle too far: for, although such characters when used with discretion are most valuable, the reverse might be the case if universally adopted.

By these characters alone we distinguish plants apart from the science of botany; and it is by the same characters that plants are distinguished by the uninitiated. If therefore there is so marked a distinction in the habit of individuals, it appears quite evident that we may reduce those characters to system. But we must recollect that nature presents no artificial system, but one uniform series of individuals, from the

most simple to the most highly organized, and between which no intermediate state can be supposed to exist. It is therefore necessary that we should form an accurate knowledge of each individual, before any system can be adopted; and it is only by investigating thoroughly each character in all its relations to certain sets of individuals, that we are enabled to distinguish each individual of any particular group, in language sufficiently explicit to separate it from those immediately preceding it.

THIRTEENTH MEETING-April 29, 1850.

J. B. YATES, Esq., in the Chair.

Mr. R. ORMEROD SMITH and WILLIAM IHNE, Ph.D., were elected members of the Society.

Mr. J. P. G. SMITH exhibited some butterflies from Para, hitherto unknown in England-the Callithea sapphira and C. leprieuri.

Dr. INMAN then read a paper upon The Distinction between Animal and Vegetable Life.

He passed in review most of the tests which have been hitherto applied to determine this knotty question. He dwelt particularly upon the motions of vegetables and the power that the spores of many of the minute Confervæ had of locomotion, and showed that the velocity of their swimming exceeded that of the Rotiferæ, a comparatively highly organized class of animals. These spores became fixed in the subsequent part of their career.

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He then spoke of the researches of Mayer and Ralfs upon this subject, and pointed out the nature of the test they proposed. This was essentially a chemical test. It was well known that all vegetables more or less secreted starch, or a substance which could be converted into starch by the agency of sulphuric acid. Tincture of Iodine rendered starch blue if, therefore, on the application of this substance any so called animalcule turned blue, or had blue spots in its interior-if at the same time it could be shown there was no means by which starch could have been introduced from without-the individual might at once be put down as belonging to the vegetable kingdom. This test had now been applied to many creatures supposed by Ehrenberg to be animal, and had proved them to belong to the lowest forms of the vegetable world.

This point, ingenious though it was, and conclusive in its nature, did not apply to those aquatic things which did not produce starch; and there was still in the minds of some a doubt about the proper locality of the sponge.

The power of abstracting silex from its combinations was very remarkable both in the lower forms of animal and vegetable life; the sponge contained an enormous quantity in the form of spicules, and so did many alcyonia. The genus Navicula, which had a silecious lorica or shell, and which he considered as vegetable, not only could appropriate silex from solutions, but it was enabled to dissolve large fragments of sand and to reapply this to the formation of its external shell. In the interior of the shells of this genus, he had often seen grains of sand varying in appearance from a large shapeless angular mass to a minute round spec. This was proved to be silica, by its resisting heat and nitric acid.

Some mosses had the power of dissolving and appropriating the silex in glass.

The author quoted largely from Ralfs' "Desmidiæ,” and other works on the same subject.

FOURTEENTH MEETING-May 13, 1850.

J. B. YATES, Esq., in the Chair.

The Rev. H. H. HIGGINS exhibited a beautifully ornamented weapon, with a heavy iron handle, and a large spiked ball suspended from it by a peculiarly formed chain. They were called Morning Stars, and something of the kind was to be seen in the Tower of London, though of a different make. He had no means of ascertaining its age, but considered it as probably older than the 15th century.

Mr. YATES thought it of still greater antiquity, and that it was probably Scandinavian.

The PRESIDENT read a letter from Dr. E. Henderson, stating that he was engaged in the construction of an Astronomical Clock, which by means of very intricate calculus, would obviate the errors which arise in the most accurate instru

ments at present in use. It will go one hundred years without winding up, and will contain about one hundred and seventy wheels and pinions, and more than three hundred distinct pieces. Besides indicating correlatively the true sidereal and mean Time, it will point out the days of the Month and Week, the Phases of the Moon, the Tides at various ports, the rising and setting of the Sun, etc., etc. The thanks of the Society were voted to Dr. Henderson.

The paper for the evening was entitled—