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buds from other individuals, and remaining connected with them. This condition prevails in all the immovable Polyparia and Hydraria, and I say intentionally in the immovable ones; for, in the movable communities, such as Renilla, Pennatula, etc., among Polyps, and all the Siphonophorae among Acalephs, we must still further distinguish another kind of individuality, which I know not how to call properly, unless the name of complex individuality may be applied to it. In complex individuality a new element is introduced, that is not noticeable in the former case. The individuals of the community are not only connected together, but, under given circumstances, they act together as if they were one individual, while at the same time each individual may perform acts of its own. As to the specific differences observed among Acalephs, there is as great a diversity between them as between their individuals. In some types of this class the species are very uniform; all the individuals belonging to one and the same species resembling one another very closely, and exhibiting hardly any difference among themselves, except such as arises from age. This identity of the individuals of one and the same species is particularly striking among the Ctenophorae. In this order there are not even sexual differences among the individuals, as they are all hermaphrodites. In the Discophorae proper a somewhat greater diversity prevails. In the first place we notice male and female individuals, and the difference between the sexes is quite striking in some genera, as, for instance, in Aurelia. Next there occur frequent deviations, among them, in the normal number of their parts; their body consisting frequently of one or two spheromeres more than usual, sometimes, even, of double normal number, or of a few less. And yet, year after year, the same Discophorae reappear upon our shores, with the same range of differences among their individuals. Among Hydroids polymorphism prevails to a greater or less extent, besides the differences arising from sex. Few species have only one kind of individuals. Mostly the cycle of individual differences embraces two distinct types of individuals, one recalling the peculiarities of common Hydrae, the other those of Medusae; but even the Hydra type of one and the same species may exhibit more or less diversity, there being frequently two kinds of Hydrae united in one and the same community, and sometimes even a larger number of heterogeneous Hydrae. And this is equally true, though to a less extent, of the Medusa type. Yet among Siphonophorae there are generally at least two kinds of Medusae in one and the same community. But notwithstanding this polymorphism among the individuals of one and the same community, genetically connected together, each successive generation reproduces the same kinds of heterogeneous individuals, and nothing but individuals linked together in the same way. Surely we have here a much greater diversity of individuals, born one from the other, than is exhibited by the most diversified breeds of our domesticated animals; and yet all these heterogeneous individuals remain true to their species, in once case as in the other, and do not afford the slightest evidence of a transmutation of species. Would the supporters of the fanciful theories lately propounded, only extend their studies a little beyond the range of domesticated animals, would they investigate the alternate generations of the Acalephs,

thé extraordinary modes of development of the Helminth, the reproduction of the Salpae, etc., etc., they would soon learn that there are, in the world, far more astonishing phenomena, strictly circumscribed between the natural limits of unvarying species, than the slight differences produced by the intervention of men, among domesticated animals, and, perhaps, cease to be so confident as they seem to be, that these differences are trustworthy indications of the variability of species. For my own part I must emphatically declare that I do not know a single fact tending to show that species do vary in any way, while it is true that the individuals of one and the same species are more or less polymorphous. The circumstance, that naturalists may find it dificult to trace the natural limits of any one particular species, or the mistakes they may make in their attempts to distinguish them, has nothing whatsoever to do with the question of their origin.

There is another feature of the species of Acalephs which deserves particularly to be noticed. All these animals are periodical in their appearance, and last for a short period, in their perfect state of development. In our latitude most Medusae make their appearance, as Ephyrae, early in the Spring, and rapidly enlarge to their full size. In September and October they lay their eggs and disappear; the young hatched from the eggs move about, as Planulae, for a short time, and then become attached, as Scyphostomes, and pass the winter in undergoing their Strobila metamorphosis. The Ctenophorae appear also very early, and lay their eggs in the autumn, passing the winter as young, and growing to their full size towards the beginning of the summer. Among the Hydroids there is more diversity in their periodicity. Hydraria are found all the year round; but the Medusae buds, the free Medusae, and the Medusaria make their appearance in different seasons, in different species. Some bring forth Medusae buds and free Medusae or Medusaria during winter; others, and in our latitude this is the case with by far the largest number of the Hydroids, produce their Medusae brood in the spring; a few breed later, in the summer or in the autumn ; so that, notwithstanding the regularity of their periodical return, Acalephs may be studied, in some condition or other, during the whole year.

When considering Individuality and Specific Differences, as manifested in the class of Acalephs, I have taken an opportunity of showing, upon general grounds how futile the arguments are upon which the theory of transmutation of species is founded. Having now shown that that class is circumscribed within definite limits, I may be permitted to add here a few more objections to that theory, based chiefly upon special grounds, connected with the characteristics of classes. If there is any thing striking in the features which distinguish classes, it is the def. initeness of their structural peculiarities; and this definiteness goes on increasing, with new and additional qualifications, as we pass from the class characters to those which mark the orders, the families, the genera, and the species. Granting, for the sake of argument, that organized beings living at a later period may have originated by a gradual change of those of earlier periods, one of the most characteristic features of all organized beings remains totally unexplained by the various

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theories brought forward to explain that change; the definiteness-of their respective groups, be they ever so comprehensive, or ever so limited, combined with the greatest inequality in their numeric relations. There exist a few thousand Mammalia and Reptiles, and at least three times their number of Birds and Fishes. There may be twenty thousand Mollusks; but there are over a hundred thousand Insects, and only a few thousand Radiates. And yet the limits of the class of Insects are as well defined as those of any other class, with the only exception of the class of Birds which is unquestionably the most definite in its natural boundaries, Now the supporters of the transmutation theory may shape their views in whatever way they please to suit the requirements of the theory, instead of building the theory upon the facts of Nature, they never can make it appear that the definiteness of the characters of the class of Birds is the result of a common descent of all Birds, for the first Bird must have been brother or cousin to some other animal that was not a Bird, since there are other animals besides Birds in this world, to no one of which any bird bears as close a relation as it bears to its own class. The same argument applies to every other class; and as to the facts, they are fatal to such an assumption, for Geology teaches us that among the oldest inhabitants of our globe known, there are representatives of nine distinct classes of animals, which by no possibility can be descendants of one another, since they are cotemporaries,

The same line of argument and the same class of facts forbid the assumption that either the representatives of one and the same order, or those of one of the same family, or those of one of the same genus should be considered as lineal descendants of a common stock; for orders, families and genera are based upon different categories of characacters, and not upon more or less extensive characters of the same kind, as I have shown years ago (Vol. I, p. 150 to 163), and numbers of different kinds of representatives of these various groups, make their appearance simultaneously in all the successive geological periods. There appear together Corals and Echinoderms of different families and of different genera in each successive geological formation, and this is equally true for Bryozoa, Brachiopods and Lamellibranchiata, for Trilobites and the other Crustacea, in fact for the representatives of all the classes of the animal kingdom, making due allowance for the period of the first appearance of each; and at all times and in all classes the representatives of these different kinds of groups are found to present the same definiteness in their characteristics and limitation, Were the transmutation theory true, the geological record should exhibit an uninterrupted succession of types blending gradually into one another. The fact is that throughout all geological times each period is characterized by definite specific types, belonging to definite genera, and these to definite families, referable to definite orders, constituting definite classes and definite branches, built upon definite plans. Until the facts of Nature are shown to have been mistaken by those who have collected them, and that they have a different meaning from that now generally assigned to them, I shall therefore consider the transmutation theory as a scientific mistake, untrue in its facts, unscientific in its method, and mischievous in its tendency.

Cambridge, June 30, 1860.

2. Anleitung zur Organischen und Gasanalyse von J. SCHIEL. Erlangen, 1860. 260 pp., 8vo.—This introduction to elementary organic and gas analysis, by our adopted countryman Dr. Schiel of St. Louis, contains a very full, yet concise, account of all of the approved methods, and is an excellent hand-book of these subjects. Many of the refinements of research which the text-books do not notice, and newly discovered processes or apparatus that are beginning to displace those hitherto in vogue, we find satisfactorily described in these pages, The best and simplest methods for taking the specific gravity of liquids, for determining melting and boiling points are given, and the admirable process of Simpson for the quantitative determination of nitrogen as well as that of Natanson for taking vapor densities are fully described.

The chapters on Gas Analysis present in a clear manner the important parts of this subject. An instructive section of the book is occupied with an exposition of the mathematical principles which apply to the discussion of experimental results and the correction of errors of observation.

We believe that this treatise will be of great service in the hands of students, and by its careful selection and full description of the methods that unite simplicity and accuracy, will help to inspire them with the animus of scientific research.


1. Parhelia seen at Weld, Franklin Co., Me. ; by STILLMAN MASTERMAN, (in a letter to the Editors).-Messrs. Editors:—I send you the following account of a parhelion seen by myself, at this place on the 21st instant, at 10h 45un A. M.

A light haze was spread over the sky at the time, for the most part so thin as to be scarcely visible, but at a few points coming out in lenticular patches of well-marked cirrus, . When first noticed at the time above stated, the meteor presented the appearance delineated in the accompanying drawing The circle A B was about 45° in diameter, having the sun in its centre; and was very brilliant, having the colors of the primary rainbow, but with the red next to the sun. It was surrounded by a bright corona of white, three or four degrees in width: the width of the colored ring A B being equal to the apparent diameter of the solar orb. Two elliptical arcs a and b were included in A B, having their middles 2° distant from the inner edge of the latter and their extremities falling within it at o 0' and PP. In color and width a and b were precisely like A B and of a like brightness. - • * Concentric with A B was the arc CD, being a little less than a semicircle, on a diameter of 95°, colored like A B with its red next to the

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sun, but of twice the width of the latter, and of dazzling brilliancy. The circle E F, with a diameter of about 60°, had its circumference in the sun and its centre vertically above him, [the arrow denoting the position of the vertical passing through the sun, and consisted of a rin of pure white, quite brilliant, and having a width equal to two-thirds the apparent diameter of the sun. The arc G was concentric with EF, and bore the same proportion in radius to the latter that CD did to A B. It was white like E.F, but not nearly so bright. The parhelia at m ms and n n' were equal to the united brilliancy of the rings intersecting at those points. At 11h 10m, all the rings had vanished but A B, which had contracted in diameter and width, and a small portion of CD immediately below the Sun. * At 11h 30m, A B had regained its former dimensions, with increased brilliancy. CD had entirely vanished. At 12h 0m, A B had contracted to 30° diameter, and become faint. All traces of the meteor had entirely vanished at 1h 30m P. M. The cirrus had in the mean time become gradually converted into cirro-cumulus, and the thin haze had completely vanished. Weld, Franklin Co., Maine, May 28th, 1860. 2. Tolles' improved Microscope Objectives.—It has been generally supposed that the further improvement of object-glasses for the microscope was to be sought in the production of flint glass of high dispersive power. I am happy to inform your readers that Mr. R. B. Tolles of Canastota, N. Y., has boldly discarded the use of flint glass of unusual dispersive power and has discovered a method of constructing glasses of as large aperture as have ever yet been made by any artist, using only such glass of uniform density as is made for ordinary optical purposes. I have recently received from Mr. Tolles a one-third inch objective, constructed on his plan, which has an aperture of 100° and is remarkable for the great amount of light transmitted even at the extreme borders of the lens. This objective is well corrected for chromatic and spherical aberration and gives excellent definition of blood corpuscles as well as of other tests appropriate for such an objective. This is a remarkably fine lass for ordinary investigations in minute anatomy and pathology. Mr. Tolles makes a one-fourth inch objective of 140° to 160° aperture, and a one-eighth inch of 160° to 175° aperture. I am inclined to think Mr. Tolles' glasses are unsurpassed by any object-glasses for the microscope that have yet been made in this country or elsewhere. M. C. WHITE. New Haven, June 10, 1860.

3. Application of Photography in construction of Micrometers.-The successful application of photography in the construction of imicrometers, has been made by Mr. Clarence Morfit of the U. S. Assay Office, New York. It is merely the reduction of a large scale of exact dimensions and divisions to a definite size suitable for microscopic instruments. A scale of ten inches divided into inches and tenths of an inch has been reduced in this manner to one-twentieth of an inch, thus making its smallest divisions equal to one two-thousandth part of an inch square. The method is simple, accurate and economical. Moreover, the micrometer has the advantage of giving the exact measurement of the object in frac

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