destroyed until immediately before death. On opening the thorax, the heart was found contracting rythmically. There was a considerable quantity of frothy secretion in the bronchial tubes, and this renders it difficult to determine if the asphyxia, by which the action of the heart was finally arrested, was nervous or pulmonary; that is, whether the nervous system was affected by the want of aëration of the blood, or whether the respiratory movements ceased in consequence of the action of the acid directly on the nervous system. The latter opinion I think the more probable.

Sulphuric acid, when introduced into the veins, gives rise to exactly the same phænomena, the only organ on which it appears to exert any marked effect being the lungs, although slight nervous symptoms are produced when a considerable quantity has been introduced into the blood. The action of these substances when injected into the arteries, and thus applied directly to the brain and over the system, without previously passing through the lungs, is evidently on the nervous system. Two drachms of the diluted acid, mixed with four drachms of water, were injected into the left axillary artery, so as to pass into the aorta; in ten seconds all movements ceased; there was a slight spasm, which relaxed in a few seconds. During the continuance of the spasm, the pressure in the arterial system was slightly increased, but it rapidly declined, so that I think the passage of the blood through the systemic capillaries is facilitated, rather than impeded by these substances. All effective contractions of the heart ceased a minute after death, probably owing to the shock produced by the sudden annihilation of the functions of the nervous system, for it retained its irritability some minutes after death.

With these experiments I conclude the first part of the series of researches which I propose to undertake for the elucidation of this branch of physiology. I have been engaged on it for the last six years, but I trust the results obtained fully repay the labour that has been bestowed on it. The action on the animal œconomy of the compounds of twenty-nine of the most important elements has been experimentally investigated, and the facts which have been observed have led to the discovery of a new law in vital chemistry which had escaped the attention of former observers, viz. that the reactions which take place between the elements of the living body and inorganic compounds are not governed by the ordinary chemical properties of these substances, but depend on certain properties they possess connected with their isomorphous relations. The verification of this law enables us to undertake the investigation of the higher chemical phænomena of living bodies from an entirely new point of view, whilst its existence accounts for the failure that has constantly attended attempts to explain the chemistry of animal life by analogy from ordinary chemical phænomena. The fact that we now possess the means of producing well-marked and definite modifications of some of the most important physiological properties of various organs, and this too by means of reagents, the laws governing whose action we are acquainted with, places in our hands an instrument for discovery which has hitherto been wanting in physiological investigations. The enumeration of some of the effects that can be produced at pleasure on the more important functions, will, I trust, suffice to lead others into this rich field of inquiry. As regards the functions of the heart, we can annihilate or increase its irritability, quicken or diminish its pulsations, render them regular or irregular, augment their force or render them weaker, destroy the contractility of the auricles, whilst that of the ventricles remains; keep up the circulation of the blood many minutes after every sign of life has disappeared, and this too more actively than when respiration was being carried on; we can facilitate or arrest the passage of the blood through the pulmonary and systemic capil

laries; produce important modifications in the functions of the brain:-in short, the injection of various substances into the arteries and veins enables us to modify all the most important functions of the body; and this, as before stated, by reagents, the laws of whose action we can fairly hope to discover. My reason for having neglected the closer investigation of these interesting phænomena, was a determination fully to establish the law of the analogous action of isomorphous substances. This having been accomplished, I shall now direct my researches to the elucidation of these secondary questions.

Report on the Actinograph. By Mr. ROBERT HUNT.

It will be remembered that in 1838 Sir John Herschel proposed an instrument for the purpose of registering the variations of the actinic or chemical rays, and published in the Philosophical Transactions a design for what he termed an Actinograph, by which it was thought both the chemical action of the direct solar rays and of the diffused daylight would be registered. Dr. Daubeny, Prof. Nichols and Mr. Thomas Jordan have severally designed, and I believe used, instruments somewhat similar, but it does not appear that any very satisfactory results have been obtained by either of these inquirers. At the York meeting I pointed out the importance of some such registration, and at the request of the committee I had an instrument constructed, which I exhibited to the Association at the Cambridge meeting. The actinograph I have been using differs but little from that proposed by Sir John Herschel, a modification of Mr. Jordan's being introduced, by which it was thought the results could be tabulated for every hour of the day. As the form of this instrument is published in the Report for 1845, it will be unnecessary to do more than describe such alterations as have suggested themselves during the past year. The triangular slit, divided into one hundred parts, has been abandoned, it being found in practice almost impossible to discriminate between the amount of coloration produced on the paper during an exposure of three minutes or six; consequently it became quite idle to attempt to register by this plan to the degree of nicety which it was hoped might be attained. A new external cylinder has therefore been constructed, in which are thirteen holes, commencing with a mere pin-hole and gradually increasing to a inch diameter. By this means thirteen bands are marked upon the sensitive paper, each one separated from the other by an unaltered line, and it becomes easy to distinguish with considerable accuracy between the tints thus produced.

Bromide of silver was the material which, from the circumstance that all the rays of the prismatic spectrum exert some influence upon it, was em ployed in procuring most of my registrations. It has however been found that under all circumstances this preparation is too sensitive, and that although in the winter, when the solar radiations are weak, it answers admirably, yet in the bright sunshine of summer it assumes too great a degree of darkness, in even diffused daylight, and during the shortest exposure to which it is exposed during the revolution of the cylinder. Many experiments have been made with other photographic preparations, and the result has been in favour of the general use of the ammonio-nitrate of silver. It is true that this paper is not impressed by all the rays of the spectrum, but, as it is acted upon by all the rays beyond the yellow ray, and as the influence of the actinic principle throughout the entire range of the spectrum is, as it appears, always equally

effected by the increased or diminished intensity of the luminous and calorific rays, and consequently that even the actinism residing in the extreme violet ray is relatively as much influenced by an increase of luminous power as that which is detected in the yellow ray itself, we may by the use of the paper prepared with the ammonio-nitrate of silver arrive at a very close approximation to the true result.

Although I have not been enabled to realize the hope I held forth last year of presenting at this meeting a register of actinic influences for the year, (which I have been prevented from doing by circumstances which I shall presently explain,) yet I have determined, most satisfactorily to my own mind, the practicability of procuring, in favourable positions, such a registration as shall afford much valuable information.

The circumstances to which I allude as those which have prevented my procuring any series of registers, are the impossibility of securing in London any position free from the constant interferences of smoke and fog, and the difficulty of placing the instrument so as to be free from the reflected radiations of adjoining buildings. The first alone is a fatal objection; for instead of securing, what is desired, a registration of the relative amount of chemical influence as compared with the quantity of light, heat, and the natural atmospheric conditions, we only get a register of the influence of smoke in absorbing the actinic rays. I therefore propose to hand over the instrument to the Association, requesting that it may be placed in a favourable position at Kew, under the attention of the excellent observer there, when I do not doubt some curious and instructive results may be obtained.

It is necessary however to state that my experience has pointed out some objections to this mode of registration, which indeed militates against the use of the actinograph as a philosophical instrument.

It is a curious fact that upon almost all kinds of photographic paper the colour produced by the solar rays at different periods of the day varies considerably. It is not a mere difference of tint, but an actual change in the colour; thus frequently the light of both morning and evening will give to chloride of silver a rose hue, whilst that of noon will change it to a bluish variety of brown. There is consequently much difficulty in deciding which is the strongest impression. Thus also the rays upon two days, when the sun appears equally bright, will in one case produce a red brown, and in the other a blue brown. It is left to the eye to decide upon the intensity of the effect produced, and with the utmost care it is frequently impossible to say whether the actinic influence is greatest on the red brown lines, or those which are blue brown.

The importance of the inquiry has been peculiarly evident during this summer; many peculiarities have been observed in the growth of plants, influenced no doubt by the solar radiations. Many of our garden flowers, particularly roses, have exhibited an abnormal condition, leaf-buds being developed in the centre of the flower, arising from the vegetative functions of the plant overpowering its reproductive functions. Again, during the intense sunshine and the prevalence of the unclouded skies of the hot weather of June and July, practical photographists found the greatest difficulty in obtaining portraits by the Daguerreotype process. At this time, although the intensity of effect produced on paper in the actinograph under the usual circumstances of summer sunlight should have been at a maximum, it was found that it was far below this point, the maximum point being represented by 120. During several experiments made at the time mentioned, the greatest effect indicated was 100; whilst the sky still being unclouded and the sun shining brightly, it often fell to 90, and sometimes indeed to 80.

ON THE INFLUENCE OF light on THE GROWTH OF PLANTS. 33

These facts show the importance, amongst many others, of some mode of registration by which these ever-varying solar influences may be carefully observed. There can be little doubt that they exert an influence, sometimes baleful, sometimes beneficial, upon the organized creation, and that we have yet to discover, in these emanations or influences, the secrets of many of the grand phænomena of the universe.

Notices on the Influence of Light on the Growth of Plants.
By Mr. ROBERT HUNT.

THE experiments connected with this very interesting inquiry have been steadily pursued, and a concluding report would have been made at this meeting, but that some experiments, which had been conducted with much care, with a view of determining the quantity of solid matter in plants grown under different circumstances, were destroyed by the hail-storm which lately prevailed over an extensive district of the metropolis, the glasses and troughs of coloured fluids being broken, and the plants themselves washed into the soil. As it was impossible to repeat this year these experiments, there was no alternative but either to present an imperfect report, or to defer the report for another year. The latter course has been chosen, and the detail of these experiments will be reserved for a future communication; I have however thought it might be attended with some advantages to state a few of the leading facts which have been determined. The order of the arrangements have been the same as those observed in the former experiments, and nearly all the results have been confirmatory of those published six years since.

The germination of seeds is peculiarly due to the influence of the actinic or chemical rays; and if these are completely isolated whilst the luminous rays are permitted to act upon the soil in which the seeds are planted, no germination will take place. This influence is exerted and is most necessary up to the point at which the first leaves begin to form, when the luminous rays are rendered necessary to effect the formation of woody fibre. It must be remembered that this was a point upon which I was at issue with some other investigators; and it is due to them that I should state, that the discrepancies between us appear to have arisen from our not observing with a sufficient degree of accuracy the point at which the two influences balance each other, previously to the more complete exercise of the exciting force of light, as distinguished from actinism. The vegetative process having been carried on until the plant arrives at its maturity, a new agency, the calorific, is more decidedly necessary to develope the reproductive functions of the plant; and then, again, the chemical rays combined with the calorific become more active than the luminous rays. In spring we find the chemical influences exerting without interference their most decided force: seeds then germinate, and young buds and shoots are developed. As soon as this is effected, the luminous rays, with the advance of the sun, become more active, and the formation of woody fibre proceeds under their particular agency; not that the chemical power becomes dormant, but it is rendered proportionally less active by the agency of light. In the late summer and the autumn the peculiar properties of the calorific rays are required, and under their agency, with diminished powers of light, the ripening of fruits and the production of seed are accomplished.

My experiments have also led me to detect some curious influences which appear to be due to dissimilar rays, and which in their action exhibit great 1846.

D

inconstancy of effect. One class of rays, the same to which Sir J. Herschel has given the name of Parathermic rays, are so subdued by the influences of the more refrangible rays, as to be nearly inactive during the spring and early summer months; and indeed in the spring they scarcely produce any effect upon dead vegetable colouring matter, unless their action is assisted by the use of some decomposing agent, such as sulphuric acid. These rays increase in power towards the autumn, and to them appears to be due the browning of the leaf.

It is well known that plants will grow in the dark, but that they do not then form chlorophylle; the formation of this colouring-matter has been an object of some attention, and I believe I have determined it to result from the joint influence of the luminous and actinic rays. Boxes of cress have been grown in the dark, and they have then been brought under the influence of a large spectrum formed by a water-prism. It has been stated by Dr.Gardner, that the plants under those circumstances exhibit a lateral movement, bending towards the yellow ray. This appears to be a mistake; the plants under the influence of the red rays bend from the light but along the line of the ray; and those exposed to the most refrangible rays turn towards it, but still in the line of the ray. Now the plants which first become green, by careful treatment in this way, are those which are exposed to the rays situated between the mean green ray and the extreme blue. The action is continued eventually to the edge of the most refrangible violet below the yellow ray. There is not any change effected beyond the visible spectrum, notwithstanding the abundance of dark chemical rays; and the change is slow where there is really the largest amount of light. I therefore conclude that the luminous rays are essential in the process, producing the decomposition of the carbonic acid and the deposition of the required carbon, which is afterwards. in all probability, combined with hydrogen under the influence of purely chemical force as exerted by the actinic principle.

Such are the main results I have obtained. I have several experiments now in progress, and I hope to be enable in another year to complete this particular branch of investigation so far as to present to the British Association a complete report.

Report on the Recent Progress of Analysis (Theory of the Comparison of Transcendentals). By R. L. ELlis, M.A.

1. THE province of analysis, to which the theory of elliptic functions belongs, has within the last twenty years assumed a new aspect. A great deal has doubtless been effected in other subjects, but in no other I think has our knowledge advanced so far beyond the limits to which it was not long since confined.

This circumstance would give a particular interest to a history of the recent progress of the subject, even did it now appear to have reached its full development. But on the contrary, there is now more hope of further progress than at the commencement of the period of which I have been speaking. When, in 1827, Legendre produced the first two volumes of his Théorie des Fonctions Elliptiques,' he had been engaged on the subject for about forty years; he had reduced it to a systematic form; and had with great labour constructed tables to facilitate numerical applications of his results. But little more, as it seemed, was yet to be done; nor does the remark of