Thus all the chief
expressive movements of the face during crying apparently
result from the contraction of the muscles round the eyes.
We shall also find that the shedding of tears depends on,
or at least stands in some connection with, the contraction
of these same muscles.
[17] Donders, ibid. p. 36.
In some of the foregoing cases, especially in those of sneezing and coughing,
it is possible that the contraction of the orbicular muscles may serve
in addition to protect the eyes from too severe a jar or vibration.
I think so, because dogs and cats, in crunching hard bones, always close
their eyelids, and at least sometimes in sneezing; though dogs do not
do so whilst barking loudly. Mr. Sutton carefully observed for me
a young orang and chimpanzee, and he found that both always closed
their eyes in sneezing and coughing, but not whilst screaming violently.
I gave a small pinch of snuff to a monkey of the American division,
namely, a Cebus, and it closed its eyelids whilst sneezing; but not on
a subsequent occasion whilst uttering loud cries.
_Cause of the secretion of tears_.--It is an important fact which
must be considered in any theory of the secretion of tears from
the mind being affected, that whenever the muscles round the eyes
are strongly and involuntarily contracted in order to compress
the blood-vessels and thus to protect the eyes, tears are secreted,
often in sufficient abundance to roll down the cheeks.
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