ducing a much greater augmentation of its length than of its diameter. There is obviously a close physiological relationship between this genus and the preceding, since the condition of each individual segment of the sarcode-body must be essentially the same in each; and it is merely in the mode in which these segments are multiplied,-a character which we have seen not to be constant in different parts even of the same specimens of Orbitolites and Orbiculina,—that it differs from them.

A marked contrast to Orbitolites and Orbiculina in all their physiological characters, coexisting with an agreement in their respective plans of growth, is presented by the genera Cycloclypeus and Heterostegina; the former of which, like Orbitolites, is cyclical from the beginning, its chambers being formed in successive annuli round a central cell; whilst the latter, like Orbiculina, is spiral in the first instance, but tends, as age advances, to assume the discoidal shape and cyclical plan of growth. The genus Cycloclypeus is a new one, founded by the author upon specimens dredged-up by Sir E. Belcher off the coast of Borneo. These are the largest Foraminifera at present known to exist; the diameter of some of them being not less than 24 inches. The genus Heterostegina was formed by M. d'Orbigny; but he seems only to have been acquainted with young specimens, and has altogether misapprehended its true characters and relations. A fragment of the flattened spire of Heterostegina could scarcely be distinguished from a marginal portion of the disk of Cycloclypeus; so close is the conformity between the two, as regards the form and relations of the chambers, their mode of communication, and the structure of their shelly envelope. Each chamber, as in Nummulites, has its own proper wall, so that the partition between the adjacent chambers, whether of the same row or of different rows, is double; and between its two lamella there is interposed an additional stratum of shell that belongs to neither. This additional stratum is thin, in the septa dividing adjacent chambers of the same row; but it is much thicker, and forms a much more complete separation, in the septa intervening between different rows. It is traversed by a canal-system, analogous to that existing in Nummulites; which the author believes to be occupied in the living state by threads of sarcode, and to be specially destined for the nutrition of the 'intermediate skeleton' formed by the aggregate of these inter

posed lamellæ. The chamber is covered-in above and below by successive layers of a minutely-tubular and peculiarly-compact shellsubstance, resembling dentine in its general aspect; certain parts of this, however, are non-tubular, and form cones, of which the bases appear on the surface as minute rounded tubercles. The adjacent chambers of the same row do not seem to communicate with each other; but each chamber communicates with two chambers of the previously-formed row, and, in like manner, with two of the subsequently-formed row, by narrow passages, the number and position of which are by no means constant. These passages seem to afford the principal means whereby the segments of the sarcode-body occupying the inner chambers, can be nourished from the exterior; but it is by no means impossible that the tubuli of the shelly laminæ that invest the chambers above and below, may also be subservient to this purpose, since, however numerous may be the laminæ, the tubuli are continued through them all from the cavity of the chamber to the external surface.

The almost entire separation of the segments of the sarcode-body in these two genera, the investment of each of them with its own proper envelope of shell, the minutely-tubular structure and firm consistence of the shell-substance, and the interposition of the intermediate skeleton with its canal-system, are features that place them in such marked contrast with Orbitolites and Orbiculina, that, notwithstanding their conformity to those two genera in their respective plans of growth, it is scarcely possible for them to be more widely removed in everything that relates to their respective physiological conditions.

From a comparison of the five genera whose structure has been thus elucidated, the author deduces the conclusion that, in this class, external form, which depends exclusively on plan of growth, affords no clue whatever to internal structure; and that the latter alone, as the exponent of the physiological condition of the animal, can afford the basis of a natural classification.

XI. "Electro-Physiological Researches."-Tenth Series. Part I. By Signor CARLO MATTEUCCI, Professor in the University of Pisa. Communicated by MICHAEL FARADAY, D.C.L., F.R.S. &c. Received June 12, 1856.

(Abstract.)

In the first section of this part of his Memoir, Professor Matteucci treats of the heat developed by muscles during contraction. Adverting to earlier experiments by other inquirers, in which a rise of temperature was observed to take place in the contracting muscle while the blood still continued to circulate through it, and where, consequently, it remained uncertain how far the effect might not be due to a modification of the circulation, the author describes his own experiments, by which it is shown that the muscles of frogs, after all circulation of the blood has ceased, and by the sole act of contraction, cause a rise of temperature amounting to about half a degree Centigrade.

The second section is devoted to the consideration of the electric current exhibited by muscles at rest, and experiments are adduced in illustration of the following propositions :

a. The electro-motive power of a cut muscle is independent of the size of its transverse section.

b. The electro-motive power increases with the length of the muscle.

c. The electro-motive property of the muscles of living or recently killed animals is greater in mammals and birds than in fish and amphibia. The duration of this force, which in all cases decreases most rapidly in the first moments after death, is greater in fish and amphibia than in the higher orders of animals.

d. The nerves have no direct influence on the electro-motive force of muscles. In general, all causes which exert an influence on the physical structure and chemical composition of muscles, so as to modify, in ways unknown, their irritability or contractility, act equally on their electro-motive power.

Prof. Matteucci here takes occasion to state, that he has verified the important discovery of Du Bois Reymond, of the existence of an

electric current in portions of nerve detached from the body,-a current which, like that of muscle, passes, in the galvanometer, from the surface of the nerve to the interior. He adds, that he could perceive no marked difference in the relative duration of the electromotive power of muscle and nerve.

In the third section, the author discusses anew, and with the aid of fresh experiments, the phenomenon originally named by him induced contraction, in which the nerve of a "galvanoscopic limb" of a frog, being laid on a muscle of a living or recently killed animal, is stimulated by the contraction of that muscle, so as to cause at the same moment contraction in the muscles of the galvanoscopic limb. He endeavours to show, that this phenomenon is due to an actual electric discharge, which takes place in a muscle at the moment of contraction, in an opposite direction to the ordinary current of the muscle while at rest. The deviation of the galvanometer-needle during the contraction of a muscle, which occurs in an opposite direction to that previously caused by the electric current generated by the muscle while at rest, was ascribed by M. Du Bois Reymond to the diminution or cessation of the latter current when the muscle contracts, and to the operation in such circumstances of the secondary polarity of the platinum plates of the galvanometer. Professor Matteucci, however, adduces various experiments to show, that, by certain arrangements described, he is able entirely to prevent the occurrence of secondary polarity, and that nevertheless the deviation of the needle takes place.

After adverting to the want of reliable data on which to found an explanation of the physical cause of the phenomenon in question, the author hints, that as there is no analogy between the form of the voltaic electromotor and that of the molecular electromotor, it is not impossible to conceive that the change of form which takes place in a muscle during contraction may be momentarily followed by the inversion of the muscular current in the exterior arc. He observes, that examples are not wanting, taken from certain cases of electrodynamic induction, and also of voltaic circuits, in which this inversion of the current can be obtained by a change in the form, or relative distance of different parts of the circuit; but he adds, that this is a new field of inquiry, which cannot be given up to merely hypothetical

views.

The last section of the paper is devoted to the consideration of the mechanical effects of muscular contraction; and experiments are stated with a view to compare the effective work of a muscular contraction, as determined empirically with the work calculated according to the principles of the dynamical theory of heat.

Employing the dynamometer already described in the fourth series of his researches, the author has found that the mechanical work effected by a single contraction of the gastrocnemius muscle of a frog may be expressed by 0-00001457 kilogramme-metres. Determining next the quantity of zinc required to be oxidated in the pile in order to excite a single contraction, he finds that the force developed by the muscle is enormously greater than could be accounted for on the supposition that it is produced by the conversion into muscular energy of the equivalent of electricity corresponding to the quantity of zinc oxidated. He accordingly concludes, that the electric current which excites a muscle to action does not represent the force exerted by the muscle, which is more probably to be referred to the chemical changes, such as oxidation, which take place in the muscular tissue during contraction. The consideration of this branch of the inquiry will form the subject of the second part of the Memoir.

XII. "On the Existence of Multiple Proportion in the quantities of Heat produced by the Chemical Combination of Oxygen and other bodies." By THOMAS WOODS, M.D. Communicated by Professor STOKES, Sec. R.S.

Received

June 7, 1856.

(Abstract.)

This paper is, in substance, the same as a former paper, bearing a similar title, read before the Royal Society on the 10th January 1856, but contains a more detailed account of the mode of performing the experiments. A repetition of the experiments mentioned in the former paper has led to very nearly the same numerical results, except in the case of molybdenum, which is found to give 4.8 thermal units by combining with oxygen, instead of 3.38, the number formerly given.