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CANTHARIDES, or SPANISH FLIES
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See also:CANTHARIDES, or See also:SPANISH FLIES , the See also:common See also:blister-beetles (Cantharis vesicatoria) of See also:European See also:pharmacy. They are See also:bright, iridescent, See also:golden-See also:green or bluish-coloured beetles (see See also:COLEOPTERA), with the See also:breast finely punctured and pubescent, See also:head and See also:thorax with a See also:longitudinal channel, and elytra with two slightly elevated lines. The See also:insect is from See also:half-an-See also:inch to an inch in length, and from one to two lines broad, the See also:female being broader in the See also:abdomen and altogether larger than the male. It is a native of the See also:south of See also:Europe, being found in See also:Spain, See also:France, See also:Germany, See also:Italy, See also:Hungary and the south of See also:Russia, and it is also obtained in See also:Siberia. The Spanish See also:fly is also occasionally found in the south of See also:England. The See also:insects feed upon ash, See also:lilac, See also:privet and See also:jasmine leaves, and are found more rarely on See also:elder, See also:rose, See also:apple and See also:poplar trees. Their presence is made known by a powerful disagreeable odour, which penetrates to a considerable distance. They are collected for use at See also:late evening or See also:early See also:morning, while in a dull bedewed See also:condition, by shaking them off the trees or shrubs into cloths spread on the ground; and they are killed by dipping them into hot See also:water or See also:vinegar, or by exposing them for some See also:time over the vapour of vinegar. They are then dried and put up for preservation in See also:glass-stoppered bottles; and they require to be very carefully guarded against mites and various other See also:minute insects, to the attacks of which they are peculiarly liable. It has been shown by means of spectroscopic observations that the green See also:colour of the elytra, &c., is due to the presence of See also:chlorophyll; and that the See also:variations of the spectral bands are sufficient, after the See also:lapse of many years, to indicate with some certainty the See also:kind of leaves on which the insects were feeding shortly before they were killed. Cantharides owe their value to the presence of a See also:peculiar chemical principle, to which the name cantharidin has been given. It is most abundant in large full-grown insects, while in very See also:young specimens no cantharidin at all has been found. From about one-See also:fourth to rather more than one-half per cent. of cantharidin has been obtained from different samples; and it has been ascertained that the elytra or wing-sheaths of the insect, which alone are used in pharmacy, contain more of the active principle than the soft parts taken together; but apparently cantharidin is most abundant in the eggs and generative See also:organs. Cantharidin constitutes from 1 to r % of cantharides. It has the See also:formula C1oH1204, and on See also:hydrolysis is converted into cantharinic See also:acid, C10H1405. It crystallizes in colourless plates and is readily soluble in See also:alcohol, See also:ether, &c., but not in water. The See also:British Pharmacopeia contains a large number of preparations of cantharides, but the only one needing See also:special mention is the See also:tincture, which is meant for See also:internal See also:administration; the small dose is noteworthy, five minims being probably the maximum for safety. The See also:external See also:action of cantharides or cantharidin is extremely characteristic. 'When it is applied to the skin there are no obvious consequences for some See also:hours. Thereafter the See also:part becomes warm and painful, owing to marked See also:local vascular See also:dilatation. This is the typical rubefacient action. Soon after-wards there is an See also:accumulation under the epidermis of a serum derived from the dilated See also:blood-vessels. The numerous small blisters or vesicles thus derived coalesce, forming a large See also:sac full of " blister-fluid." The See also:drug is described as a See also:counter-irritant, though the explanation of this action is very doubtful. Apparently there is an See also:influence on the afferent nerves of the part which causes a reflex contraction—some authors say dilatation—of the vessels in the internal organs that are under the See also:control of the same segment of the See also:nervous See also:system as that supplying the See also:area of skin from which the exciting impulse comes. When applied in this See also:fashion a certain quantity of the cartharides is absorbed. Taken internally in any but minute doses, the drug causes the most severe gastro-intestinal irritation, the vomited and evacuated matters containing blood, and the patient suffering agonizing See also:pain and extreme depression. The further characteristic symptoms are displayed in the genito-urinary See also:tract. The drug circulates in the blood in the See also:form of an albuminate and is slowly excreted by the kidneys. The effect of large doses is to cause See also:great pain in the renal region and urgent wish to micturate. The urine is nevertheless small in amount and contains albumen and blood owing to the local inflammation produced in the See also:kidney by the passage of the See also:poison through that See also:organ. The drug often has a marked aphrodisiac action, producing priapism, or in the female See also:sex the onset of the catamenia or See also:abortion. Cantharides is used externally for its counter-irritant action. There are certain definite contra-indications to its use. It must not be employed in cases of renal disease, owing to the risks attendant upon absorption. It must always be employed with caution in the See also:case of elderly persons and See also:children; and it must not be applied to a paralysed See also:limb (in which the See also:power of healing is deficient), nor to parts upon which the patient lies, as other-See also:wise a See also:bed-sore is likely to follow its use. The drug is administered internally in certain cases of See also:impotence and occasionally in other conditions. Its criminal employment is usually intended to heighten sexual See also:desire, and has frequently led to See also:death. The toxic symptoms have already been detailed, the patient usually dying from See also:arrest of the renal functions. The treatment is far from satisfactory, and consists in keeping up the strength and diluting the poison in the blood and in the urine by the administration of bland fluids, such as soda-water, See also:milk and See also:plain water, in quantities as large as possible. External warmth should also be applied to the regions specially affected by the drug. A very large number of other insects belonging to the same See also:family possess blistering properties, owing to their containing cantharidin. Of these the most remarkable is the Telini " fly " of See also:India (Mylabris cichorii), the range of which extends from Italy and See also:Greece through See also:Egypt and central See also:Asia as far as See also:China. It is very See also:rich in cantharidin, yielding fully twice as much as See also:ordinary cantharides. Several green-coloured beetles are, on See also:account of their colour, used as adulterants to cantharides, but they are very easily detected by examination with the See also:eye, or, if powdered, with the See also:microscope. Additional information and CommentsThere are no comments yet for this article.
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