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etails about their weeping； supported as they are by the positive assertion of the keeper in the Zoological Gardens。 It is certain that the two elephants in the Gardens； when they began to trumpet loudly； invariably contracted their orbicular muscles。 I can reconcile these conflicting statements only by supposing that the recently captured elephants in Ceylon； from being enraged or frightened； desired to observe their persecutors； and consequently did not contract their orbicular muscles； so that their vision might not be impeded。 Those seen weeping by Sir E。 Tennent were prostrate； and had given up the contest in despair。 The elephants which trumpeted in the Zoological Gardens at the word of command； were； of course； neither alarmed nor enraged。
From the several foregoing cases with respect to Man； there can； I think； be no doubt that the contraction of the muscles round the eyes； during violent expiration or when the expanded chest is forcibly compressed； is； in some manner； intimately connected with the secretion of tears。 This holds good under widely different emotions； and independently of any emotion。 It is not； of course； meant that tears cannot be secreted without the contraction of these muscles； for it is notorious that they are often freely shed with the eyelids not closed； and with the brows unwrinkled。 The contraction must be both involuntary and prolonged； as during a choking fit； or energetic； as during a sneeze。 The mere involuntary winking of the eyelids； though often repeated； does not bring tears into the eyes。 Nor does the voluntary and prolonged contraction of the several surrounding muscles suffice。 As the lacrymal glands of children are easily excited； I persuaded my own and several other children of different ages to contract these muscles repeatedly with their utmost force； and to continue doing so as long as they possibly could； but this produced hardly any effect。 There was sometimes a little moisture in the eyes； but not more than apparently could be accounted for by the squeezing out of the already secreted tears within the glands。
The nature of the relation between the involuntary and energetic contraction of the muscles round the eyes； and the secretion of tears； cannot be positively ascertained； but a probable view may be suggested。 The primary function of the secretion of tears； together with some mucus； is to lubricate the surface of the eye； and a secondary one； as some believe； is to keep the nostrils damp； so that the inhaled air may be moist；＇21＇ and likewise to favour the power of smelling。 But another； and at least equally important function of tears； is to wash out particles of dust or other minute objects which may get into the eyes。 That this is of great importance is clear from the cases in which the cornea has been rendered opaque through inflammation； caused by particles of dust not being removed； in consequence of the eye and eyelid becoming immovable。＇22＇ The secretion of tears from the irritation of any foreign body in the eye is a reflex action；that is； the body irritates a peripheral nerve which sends an impression to certain sensory nerve…cells； these transmit an influence to other cells； and these again to the lacrymal glands。 The influence transmitted to these glands causes； as there is good reason to believe； the relaxation of the muscular coats of the smaller arteries； this allows more blood to permeate the glandular tissue； and this induces a free secretion of tears。 When the small arteries of the face； including those of the retina； are relaxed under very different circumstances； namely； during an intense blush； the lacrymal glands are sometimes affected in a like manner； for the eyes become suffused with tears。
It is difficult to conjecture how many reflex actions have originated； but； in relation to the present case of the affection of the lacrymal glands through irritation of the surface of the eye； it may be worth remarking that； as soon as some primordial form became semi…terrestrial in its habits； and was liable to get particles of dust into its eyes； if these were not washed out they would cause much irritation； and on the principle of the radiation of nerve…force to adjoining nerve…cells； the lacrymal glands would be stimulated to secretion。 As this would often recur； and as nerve…force readily passes along accustomed channels； a slight irritation would ultimately suffice to cause a free secretion of tears。
＇21＇ Bergeon； as quoted in the ‘Journal of Anatomy and Physiology；' Nov。 1871； p。 235。
＇22＇ See； for instance； a case given by Sir Charles Bell； ‘Philosophical Transactions；' 1823； p。 177。
As soon as by this； or by some other means； a reflex action of this nature had been established and rendered easy； other stimulants applied to the surface of the eyesuch as a cold wind； slow inflammatory action； or a blow on the eyelids would cause a copious secretion of tears； as we know to be the case。 The glands are also excited into action through the irritation of adjoining parts。 Thus when the nostrils are irritated by pungent vapours； though the eyelids may be kept firmly closed； tears are copiously secreted； and this likewise follows from a blow on the nose； for instance from a boxing…glove。 A stinging switch on the face produces； as I have seen； the same effect。 In these latter cases the secretion of tears is an incidental result； and of no direct service。 As all these parts of the face； including the lacrymal glands； are supplied with branches of the same nerve； namely； the fifth； it is in some degree intelligible that the effects of the excitement of any one branch should spread to the nerve…cells or roots of the other branches。
The internal parts of the eye likewise act； under certain conditions； in a reflex manner on the lacrymal glands。 The following statements have been kindly communicated to me by Mr。 Bowman； but the subject is a very intricate one； as all the parts of the eye are so intimately related together； and are so sensitive to various stimulants。 A strong light acting on the retina； when in a normal condition； has very little tendency to cause lacrymation； but with unhealthy children having small； old…standing ulcers on the cornea； the retina becomes excessively sensitive to light； and exposure even to common daylight causes forcible and sustained closure of the lids； and a profuse flow of tears。 When persons who ought to begin the use of convex glasses habitually strain the waning power of accommodation； an undue secretion of tears very often follows； and the retina is liable to become unduly sensitive to light。 In general； morbid affections of the surface of the eye； and of the ciliary structures concerned in the accommodative act； are prone to be accompanied with excessive secretion of tears。 Hardness of the eyeball； not rising to inflammation； but implying a want of balance between the fluids poured out and again taken up by the intra…ocular vessels； is not usually attended with any lacrymation。 When the balance is on the other side； and the eye becomes too soft； there is a greater tendency to lacrymation。 Finally； there are numerous morbid states and structural alterations of the eyes； and even terrible inflammations； which may be attended with little or no secretion of tears。
It also deserves notice； as indirectly bearing on our subject； that the eye and adjoining parts are subject to an extraordinary number of reflex and associated movements； sensations； and actions； besides those relating to the lacrymal glands。 When a bright light strikes the retina of one eye alone； the iris contracts； but the iris of the other eye moves after a measurable interval of time。 The iris likewise moves in accommodation to near or distant vision； and when the two eyes are made to converge。＇23＇ Every one knows how irresistibly the eyebrows are drawn down under an intensely bright light。 The eyelids also involuntarily wink when an object is moved near the eyes； or a sound is suddenly heard。 The well…known case of a bright light causing some persons to sneeze is even more curious； for nerve…force here radiates from certain nerve…cells in connection with the retina； to the sensory nerve…cells of the nose； causing it to tickle； and from these； to the cells which command the various respiratory muscles （the orbiculars included） which expel the air in so peculiar a manner that it rushes through the nostrils alone。
To return to our point： why are tears secreted during a screaming…fit or other violent expiratory efforts？ As a slight blow on the eyelids causes a copious secretion of tears； it is at least possible that the spasmodic contraction of the eyelids； by pressing strongly on the eyeball； should in a similar manner cause some secretion。 This seems possible； although the voluntary contraction of the same muscles does not produce any such effect。 We know that a man cannot voluntarily sneeze or cough with nearly the same force as he does automatically； and so it is with the contraction of the orbicular muscles： Sir C。 Bell experimented on them； and found that by suddenly and forcibly closing the eyelids in the dark； sparks of light are seen； like those caused by tapping the eyelids with the fingers； 〃but in sneezing the compression