instead of being outspread upon it. But if this be the nature of the choroïd, this structure becomes, in connexion with its peculiar position, invested with special functions. The old notion that it was a gland was not far wrong; for Luschka's researches go to prove that it is an actively secreting organ, and in all probability is concerned in the production of the cerebro-spinal fluid. And to our mind, it is a farther indication of its secreting function and of activity in it, that it becomes with advancing life so generally diseased. It evidently attracts towards it a large quantity of the earthy saltsphosphate and carbonate of lime-from the blood; for in adults concretions of those salts may always be looked for in the meshes of its vessels and in the cysts which so often arise from their epithelial coating. Again, if we look into its anatomy, we find it has numerous vessels which pass to or from it out of the cerebral substance; it is connected on one side with the pia mater, and on the other sends processes to join with the velum interpositum and the choroïd prolongations extending from that structure into the third and fourth ventricles, and with the great venæ Galeni. Moreover, it contains no true capillaries in its meshwork of vessels, and is more highly developed in man than in any other animal. These facts intimate a derivative purpose; a provision against the ill effects of undue arterial pressure and fulness in the surrounding parts; a ready channel for the transmission of arterial excess into a system of veins which immediately run into the venæ Galeni and thence into the great sinuses of the occiput.

The sinuses of the cranium are among the most remarkable conservative provisions of nature. The collection of venous blood on the periphery of the brain, in non-extensible channels so placed along its anfractuosities as to obviate the chances of pressure, is an arrangement without parallel in any other structure. The brain is too delicate an organ to be exposed to the risk of pressure from elastic-walled, extensible vessels, whether arteries or veins, at least from that of any but those of the smallest dimensions; hence the arteries are distributed and supported in the meshes of the pia mater over the whole surface of the brain, whilst outside of all the veins are collected, and pour their blood into the great sinuses. These last then constitute an interposed venous system between the cerebral and the jugular veins-a protective arrangement securing, both by their size and frequent communications, the rapid removal of blood from the cranium, and yet allowing the presence of a large quantity without detriment to the subjacent cerebral mass. For though their fibrous walls will not distend, this very circumstance tends to compel the onward progress of the blood, favoured by gravity, towards the great venous outlet at the jugular foramen; and moreover, the pressure upon them gets partial relief through the veins opening into them from the exterior of the cranium and from the diploë, and particularly through the ophthalmic vein and its branches.

These provisions for a fluctuating quantity of blood within the cranium now considered, required on account of temporary interruptions and changes of the circulation and respiration, have their

homologues in other regions in some other animals, where such interruptions are of much more frequent occurrence and continuance. We have not space to go into particulars on this head, but would refer for illustration to the anatomy of the Cetacea, in which we find arterial plexuses between the pleura and ribs and around the upper end of the spinal cord, as well as a marvellous venous plexus-its component veins without valves, like the sinuses and veins of the human brain, beneath the skin, communicating with the inferior vena cava. So likewise in diving animals such venous reservoirs exist-as, for example, in the seal-about the heart.

Some few words are needed respecting the cerebro-spinal fluid, the last of the conservative provisions connected with the cerebral circulation which we have to notice. As we observed in the earlier part of this paper, the objections raised by Virchow and Kölliker against the permeation of the cerebro-spinal liquid through all the cavities within and around the brain, are overruled by the researches of Luschka and others. Considering, therefore, its general diffusion to be proved, its importance in keeping up an equable pressure upon the brain must be admitted. Indeed, the fact that its sudden removal in animals causes a staggering faintness and convulsive movements, intimates its functional importance. And we gather the same conclusion from other facts, such as the increase of the fluid in old age, in persons in feeble health, and in cases where the arterial supply is largely cut off. In the last-named cases, its outpouring-if Schlossberger be correct, that a decrease of arterial blood involves a more rapid coagulation of the cerebral substance, and a consequent shrinking of the brain-must be particularly demanded.

Lastly, the cerebro-spinal fluid must be allowed to be something more than a mere passive agent concerned in the movements and circulation of the brain, if the choroid plexuses are, as we believe, proved to be, secretory organs, and the pia mater to be covered with an epithelium. Indeed, regarding only the structure of the pia mater, there appears to be all the elements both for serous secretion and serous absorption, and the relative preponderance of one or of the other process will be determined by the amount of pressure of the brain against its bony case. How considerable this pressure is, is demonstrated by the thrusting out of the brain when an aperture is made in the cranium, by the moulding of the outline of the cerebral convolutions in progress of time upon the hard inner table of the skull, and by the unmistakeable signs of pressure exhibited by morbid effusions on the surface of the brain. So great have some pathologists deemed the importance of the pressure between the osseous cranium and the cerebrum, that they have concluded that the very thick cranial bones encountered in many cases of chronic shrinking of the brain, prove a natural compensatory endeavour to adapt them by an extraordinary development of diploë to the reduced size of the organ.

57-XXIX.

9

1. On Poisons.

REVIEW VIII.

Art.: "Arsenic." By ALFRED S. TAYLOR, M.D., F.R.S.-London, 1859.

2. Facts and Fallacies connected with the Research for Arsenic and Antimony. By ALFRED S. TAYLOR, M.D., F.R.S.

pital Reports,' Oct. 1860.)

('Guy's Hos

3. On the Application of Electrolysis to the Detection of the Poisonous Metals in Mixtures containing Organic Matters. By CHARLES L. BLOXAM. (Quarterly Journal of Chemical Society.")

4. On the Alleged Practice of Arsenic-eating in Styria. By H. E. RosCOE, B.A., Ph.D. (Memoirs of Literary and Philosophical Society of Manchester,' 1859-60.)

5. Annales d'Hygiène. 1859.

WE propose to lay before our readers a brief account of several important points in connexion with the industrial, accidental, and criminal uses of arsenic which, within the last few years, have attracted considerable notice-viz., the commercial and industrial applications of arsenite of copper in green paper-hangings, artificial flowers, &c.; the presence of arsenic in the water and mud of rivers; the alleged practice of arsenic-eating; the effects of arsenic on lower animals; and the latest researches upon the means of its detection.

1. The commercial and industrial applications of arsenite of copper.-Self-interest and money influences for some time essayed to ignore or explain away the ill effects of paper-hangings coloured with pigment containing Scheele's green.* Facts, however, proving beyond dispute the injurious and even fatal consequences resulting to the health from the use of such papers, have been so rapidly accumulated, that those who recently doubted or denied the possibility of such an occurrence are now among the foremost to direct attention thereto. We may here enumerate a few published instances of these ill effects of green paper-hangings.

Dr. Halley,† in relating his own personal experience of the poisonous influences of the green arsenite, recorded one of the earliest examples -one which attracted considerable attention, and became the subject of dispute, as we shall have occasion subsequently to show. Dr. * Aceto-arsenite of copper, called also Schweinfurth green, Vienna green, Imperial green, Emerald green.

4

Hinds,* having suffered also himself from symptoms which he attributed to the influence of arsenic, directed his attention to the green paper of his room, and finding it to contain arsenite of copper, forthwith had it removed, whereon the symptoms disappeared. Mr. Whitehead related the case of a youth suffering under all the signs of arsenical poisoning, and in whose case all means in the shape of treatment were useless until the green paper-hangings were removed from a room which he inhabited. Dr. Wright‡ recorded his personal sufferings from the same cause, and their removal in a similar manner. Mr. Gays likewise placed before the profession his own experience of injured health, attributable to a like cause, and confirmed by Dr. Taylor's examination of the suspected paper. Mr. Kesteven stated the particulars of a case of long-continued derangement of the health, relieved by the accidental removal of a green paper, receiving confirmation by the subsequent examination thereof. Dr. Alfred Taylor¶ published an instance of conjunctivitis occurring with other symptoms of arsenical poisoning, as the result of inhabiting a room hung with green paper-hangings. The paper having been removed, the symptoms subsided, but soon afterwards returned. On close inquiry, it transpired that the patient had been dusting some books that had long stood undisturbed on his shelves. The relapse was explained by the discovery of particles of arsenite of copper in the dust on the books and shelves. Dr. Ballenden** relates also the cases of three children who, occupying a sleeping chamber newly papered with green hangings, "pined unaccountably," became emaciated, grew restless and nervous, and had involuntary twitchings of the muscles of the face, with smarting of the eyelids, ophthalmia, and gastro-enteric symptoms, from arsenical poisoning.

The latest recorded case has proved a fatal one:

"On the last day of October, a little boy, three years and a half old, was seized with sickness, chilliness, and loss of appetite; on the following day, convulsions and a semi-comatose state supervened. During the night the little sufferer became very restless, and sank into collapse. At this time a sister was also seized with convulsions, followed by violent screaming and copious dysenteric discharge from the bowels. Alternations of repose and violent tetanic convulsions continued during the day, and the little boy died thirtyeight hours after the commencement of the attack. Suspicions were aroused by the peculiarity of the symptoms, and the simultaneous seizure of the two children. Three months previously they had been attacked in the same manner, and had recovered after leaving the house for the sea-side. The second illness seized the children after their return home. It was discovered that they had within the last few days been playing with their toys in the cupboard of the breakfast-room, the room and cupboard being both papered with a green flock paper; that two or three days previously they had been amused by helping to clear out the cupboard; and that the little boy had sucked a piece of lace which he found amongst the books and toys there. The evacuations were preserved, and sent to Dr. Letheby for analysis; subsequently, the sto

• Medical Times and Gazette, Feb. 14th, 1857.

↑ British Medical Journal, Sept. 25th, 1858.

* Medical Times and Gazette, Feb. 12th, 1859. Ibid., Nov. 8th, 1859.

§ Ibid, Jan. 22, and Feb. 12, 1859. ¶ Ophthalmic Hospital Reports, Jan. 7th, 1859. ** Lancet, Feb. 4th, 1860.

mach, with its contents, part of the liver, and the sigmoïd flexure of the colon, were also forwarded, together with portions of the green paper. Dr. Letheby reported that the stomach, liver, and evacuations contained distinct traces of arsenic. His examination of the paper revealed the fact that no less than one-third of its whole weight consisted of arsenite of copper! A piece of this paper, five inches square, contained seven grains of arsenic."*

Dr. Taylor found in another sample of green paper 59 per cent. of the arsenite. The same authority reports that the quantity of this pigment consumed weekly by one manufacturer is two tons!

The symptoms manifested in the various reported accounts of the ill effects of green paper-hangings have been clearly those of chronic arsenical poisoning; and when it is further borne in mind that these symptoms disappear when the suspected paper has been removed, there can be no room for doubt on the matter. The principal symptoms observed have been-headache, conjunctivitis, hoarseness, thirst, loss of appetite, nausea, dryness of mouth and throat, aphthous ulceration of gums and mouth, diarrhoea, colicky pains, prostration, general debility, sleeplessness, cutaneous eruptions, convulsions, coma, death. A reference to any treatises on toxicology will satisfy that the above are symptoms of chronic arsenical poisoning.

In opposition to the preceding facts and conclusions, it was argued by some, that the workmen employed in making and hanging green papers do not suffer in health from their occupation. In answer to this we observe simply, that these people do suffer, especially when they work on the dry powder-cutaneous eruptions and symptoms of chronic poisoning being commonly met with under those circumstances. It is when working the pigment in a moist state that the exemption is found. The proprietor of an extensive manufactory of paper-hangings informs the writer that years past he had made up many tons of the green pigment, and did not feel any evil effects, as it was in a damp state. "We use it in our factory; the men never complain while it is darop; but when it is dry, while rolling up the pieces, some particles get detached, which produce irritation of the nostrils and skin of the face, giving rise to pimples. Some appear more susceptible to these effects than others. The eruptions go off in a few days, without the appearance of sickness or impairment of the general health." The same effects, this gentleman observes, may occur from the detachment of particles of Scheele's green from the surface of common machine papers." The arsenite of copper is laid on with gum or size, and in papers of inferior quality is readily detached by variations in atmospheric heat, or dryness, or moisture, or according as they are or are not varnished or sized. Even in the latter case it is not unattended with danger.

Our readers may remember that Dr. Alfred Taylor a few years ago removed arsenite of copper from the crust of a slice of bread that had become thus contaminated by the paint on a baker's shelves; in this case no volatilization of the poison could have taken place. It is futile to bring forward instances of

• Lancet, Nov. 24th, 1860.