(34

[Note in another hand:] pp. 170/71

(34

Ch VI.

reflex actions of any many kinds have originated; but it may perhaps be worth remarking with respect to the present case that as soon as some primordial form became semi-terrestrial in habits, & was liable to get particles of dust into its eyes, if these were not washed out they would cause much irritation; & 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 occur recur, & the [illeg] of & as nerve-force readily passes through readily passes through accustomed channels, a slight irritation wd ultimately lead to suffice to cause a free secretion of tears.) (as soon as by this or by some other means, [3 words illeg] reflex this reflex action, has once by some means once been set up, may any has once been established & rendered easy other stimulants stimulants applied to the surface of the eye, such as a blow blow on the eyelid, [2 words illeg], cold wind, slow inflammatory action, or a blow on the eyelid would cause, as we know they do, a copious secretion of tears. But it is

The lachrymal glands are also excited in a reflex manner excited to into action in through when the irritation of adjoining parts. Thus when the nostrils are irritated by pungent odours vapours acting in on the nose, with, though the eyelids may be kept firmly closed, causes the secretion of tears; as does tears are copiously secreted; & this follows from a blow on the nose, for instance with from a boxing glove. A

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manner excited to into action in through when the irritation of adjoining parts. Thus when the nostrils are irritated by pungent odours vapours acting in on the nose, with, though the eyelids may be kept firmly closed, causes the secretion of tears; as does tears are copiously secreted; & this follows from a blow on the nose, for instance with from a boxing glove. A stinging cut with a switch on the skin of the face produces, as I have seen, the same effect. In the majority of these cases the secretion of tears is an incidental result, & of no direct service.)

(72

[Note in another hand:] Desc. of Man, p. 150

(72

Ch. 3.

tail is not of much service importance to them; & if so, we might have expected that it would sometimes have become more or less rudimentary, in accordance with what we so frequently see with various other structures, more or less completely rudimentary in some related species. Whether the tail is long or quite short, it generally almost also ends in a tapering tapers towards the end; & this, I presume, may be accounted for by the atrophy of the terminal muscles through disuse together with thin arteries & nerves, & as a consequence of the terminal bones. With respect to the os coccyx, which in man & the higher apes manifestly consists of the few basal, & still tapering segments of an ordinary tail, I have heard it asked [text taped over] these have become completely [text taped over] but then

[Note in another hand:] Desc. of Man, p. 150

(71

Ch. 3.

differ to an extraordinary degree in closely related forms.

According to a popular impression, the absence of a tail makes an essential a great difference between

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related forms.

According to a popular impression, the absence of a tail makes an essential a great difference between man & the lower animals; but as those apes which come nearest to man are equally destitute of a tail, its disappearance does not here especially concern us. Nevertheless it may be well to own that no explanation, as far as I am aware, can has ever been given of the loss of the tail in some certain apes & in [text excised] Its [text excised] [illeg] however, is not