19. Hence the butcher's stall will furnish all the materials for the study of the microscopic tissues. The structure of the heart, lungs, liver, brain, and muscle may all be studied, and well studied, by using minute pieces of the flesh of the lower animals, especially of the quadrupeds.

Such portions of these animals as are not exposed for sale can be readily obtained by order from the slaughter-house. To examine with the powers of which we have been speaking, it is only necessary to cut off {246} exceedingly small pieces, tear them apart with needles, or make very delicate sections with a sharp knife.

20. INCENTIVES TO STUDY.--A complete knowledge of all minute structures is not to be expected at once, for you are here introduced into a new realm of Nature, a world of little things as vast, as wonderful, and as carefully constructed as the starry firmament,--that other realm of grand objects which the astronomer nightly scans with the telescope. It will not appear singular, therefore, if, at first, you feel strange and awkward in this new creation. With a little perseverance, however, and with the attention directed toward simple objects at the outset, it will not be long before an increasing experience will engender confidence.

21. If to all this there be added an enthusiastic study of the standard authorities on the subject, the rate of progress will be by so much the more rapid. As compared with similar studies, few possess more interest than microscopy, and to the one who pursues it with fondness, it constantly affords sources of pleasure and agreeable surprises; and in the end, often leads to new and valuable additions to the sum of human knowledge. The depths which the microscope is employed to fathom are no more completely known, than are the heights above us explored and comprehended by the astronomer.

QUESTIONS FOR TOPICAL REVIEW.

_State what you can on the following subjects_:

1. Voice and speech 227, 228 2. The organ of the voice 228, 229 3. The vocal cords 230, 231 4. The production of the voice 232, 233 5. The varieties of voice 233, 234 6. Ventriloquism 235 7. The law of the tissues 236 8. Necessity of the microscope 236 9. Convex lenses 236, 237 10. Kinds of microscope 237, 238 11. Choosing a microscope 239, 242 12. Preliminary studies 243, 244 13. The study of human tissues 244 14. The study of the inferior animals 245

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APPENDIX.

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POISONS AND THEIR ANTIDOTES.

Accidents from poisoning are of such frequent occurrence, that every one should be able to administer the more common antidotes, until the _services of a physician can be obtained_. As many poisons bear a close resemblance to articles in common use, no dangerous substance should be brought into the household without having the word _poison_ plainly written or printed on the label; and any package, box, or vial, without a label, should be at once destroyed, if the contents are not positively known.

When a healthy person is taken severely and _suddenly_ ill _soon after some substance has been swallowed_, we may suspect that he has been poisoned. In all cases where poison has been taken into the stomach, it should be quickly and thoroughly evacuated by some active emetic, which can be speedily obtained. This may be accomplished by drinking a tumblerful of warm water, containing either a tablespoonful of powdered mustard or of common salt, or two teaspoonfuls of powdered alum in two tablespoonfuls of syrup. When vomiting has already taken place, it should be maintained by copious draughts of warm water or mucilaginous drinks, such as gum-water or flaxseed tea, and tickling the throat with the finger until there is reason to believe that all the poisonous substance has been expelled from the stomach.

The following list embraces only the more common poisons, together with such antidotes as are usually at hand, to be used until the physician arrives.

POISONS.

ACIDS.--_Hydrochloric acid_; _muriatic acid_ (spirits of salt); _nitric acid_ (aqua fortis); _sulphuric acid_ (oil of vitriol).

ANTIDOTE.--An antidote should be given at once to neutralize the acid.

Strong soapsuds is an efficient remedy, and can always be obtained. It should be followed by copious draughts of warm water or flaxseed tea.

Chalk, magnesia, soda or saleratus (with water) or {248} lime-water, are the best remedies. When sulphuric acid has been taken, water should be given sparingly, because, when water unites with this acid, intense heat is produced.

_Oxalic acid._

ANTIDOTE.--Oxalic acid resembles Epsom salts in appearance, and may easily be mistaken for it. The antidotes are magnesia, or chalk mixed with water.

PRUSSIC ACID; _oil of bitter almonds_; _laurel water_; _cyanide of pota.s.sium_ (used in electrotyping).

ANTIDOTE.--Cold douche to the spine. Chlorine water, or water of ammonia largely diluted, should be given, and the vapor arising from them may be inhaled.

ALKALIES AND THEIR SALTS.--AMMONIA (hartshorn), _liquor or water of ammonia_. POTa.s.sA:--_caustic potash_, _strong ley_, _carbonate of pota.s.sa_ (pearlash), _nitrate of pota.s.sa_ (saltpetre).

ANTIDOTE.--Give the vegetable acids diluted, as weak vinegar, acetic, citric, or tartaric acids dissolved in water. Castor oil, linseed oil, and sweet oil may also be used; they form soaps when mixed with the free alkalies, which they thus render harmless. The poisonous effects of saltpetre must be counteracted by taking mucilaginous drinks freely, so as to produce vomiting.

ALCOHOL.--_Brandy_, _wine_; _all spirituous liquors_.

ANTIDOTE.--Give as an emetic ground mustard or tartar emetic. If the patient cannot swallow, introduce a stomach pump; pour cold water on the head.

GASES.--_Chlorine_, _carbonic acid gas_, _carbonic oxide_, _fumes of burning charcoal_, _sulphuretted hydrogen_, _illuminating or coal-gas_.

ANTIDOTE.--For poisoning by chlorine, inhale, cautiously, ammonia (hartshorn). For the other gases, cold water should be poured upon the head, and stimulants cautiously administered; artificial respiration. (See _Marshall Hall's Ready Method_, page 250.)

METALS.--_Antimony_, _tartar emetic_, _wine of antimony_, etc.

ANTIDOTE.--If vomiting has not occurred, it should be produced by tickling the throat with the finger or a feather, and the abundant use of warm water. Astringent infusions, such as common tea, oak bark, and solution of tannin, act as antidotes.

a.r.s.eNIC.--_White a.r.s.enic_, _Fowler's solution_, _fly-powder_, _cobalt_, _Paris green_, etc.

ANTIDOTE.--Produce vomiting at once with a tablespoonful or two of powdered mustard in a gla.s.s of warm water, or with ipecac. The antidote is hydrated peroxide of iron. If Fowler's solution has been taken, lime-water must be given. {249}

COPPER.--_Acetate of copper_ (verdigris), _sulphate of copper_ (blue vitriol), food cooked in dirty _copper vessels_, or pickles made green by _copper_.

ANTIDOTE.--Milk or white of eggs, with mucilaginous drinks (flaxseed tea, etc.), should be freely given.

IRON.--_Sulphate of iron_ (copperas), etc.

ANTIDOTE.--Carbonate of soda in some mucilaginous drink, or in water, is an excellent antidote.

LEAD.--_Acetate of lead_ (sugar of lead), _carbonate of lead_ (white lead), water kept in _leaden pipes_ or _vessels_, food cooked in _vessels_ glazed with _lead_.

ANTIDOTE.--Induce vomiting with ground mustard or common salt in warm water. The antidote for soluble preparations of lead is Epsom salts; for the insoluble forms, sulphuric acid largely diluted.

MERCURY.--_Bichloride of mercury_ (corrosive sublimate), _ammoniated mercury_ (white precipitate), _red oxide of mercury_ (red precipitate), _red sulphuret of mercury_ (vermilion).

ANTIDOTE.--The white of eggs, or wheat flour beaten up with water and milk, are the best antidotes.

SILVER.--_Nitrate of silver_ (lunar caustic).

ANTIDOTE.--Give a teaspoonful of common salt in a tumbler of water. It decomposes the salts of silver and destroys their activity.

ZINC.--_Sulphate of zinc_, etc. (white vitriol).

ANTIDOTE.--The vomiting may be relieved by copious draughts of warm water.

The antidote is carbonate of soda administered in water.

NARCOTIC POISONS.--_Opium_ (laudanum, paregoric, salts of morphia, G.o.dfrey's cordial, Dalby's carminative, soothing syrup, cholera mixtures), _aconite_, _belladonna_, _hemlock_, _stramonium_, _digitalis_, _tobacco_, _hyosciamus_, _nux vomica_, _strychnine_.

ANTIDOTE.--Evacuate the stomach by the most active emetics, as mustard, alum, or sulphate of zinc. The patient should be kept in motion, and cold water dashed on the head and shoulders. Strong coffee must be given. The physician will use the stomach pump and electricity. In poisoning by nux vomica or strychnine, etc., chloroform or ether should be inhaled to quiet the spasms.

IRRITANT VEGETABLE POISONS.--_Croton oil_, _oil of savine_, _poke_, _oil of tansy_, etc.

ANTIDOTE.--If vomiting has taken place, it may be rendered easier by copious draughts of warm water. But if symptoms of insensibility have come on without vomiting, it ought to be immediately excited by ground mustard mixed with warm water, or some other active emetic {250} and after its operation an active purgative should be given. After evacuating as much of the poison as possible, strong coffee or vinegar and water may be given with advantage.

POISONOUS FISH.--_Conger eel_, _mussels_, _crabs_, etc.