Under the opposite emotion of great joy or amusement, as long as laughter
is moderate there is hardly any contraction of the muscles round the eyes,
so that there is no frowning; but when peals of loud laughter are uttered,
with rapid and violent spasmodic expirations, tears stream down the face.
I have more than once noticed the face of a person, after a paroxysm
of violent laughter, and I could see that the orbicular muscles and those
running to the upper lip were still partially contracted, which together
with the tear-stained cheeks gave to the upper half of the face an expression
not to be distinguished from that of a child still blubbering from grief.
The fact of tears streaming down the face during violent laughter is common
to all the races of mankind, as we shall see in a future chapter.

In violent coughing especially when a person is half-choked,
the face becomes purple, the veins distended, the orbicular muscles
strongly contracted, and tears run down the cheeks. Even after
a fit of ordinary coughing, almost every one has to wipe his eyes.
In violent vomiting or retching, as I have myself experienced
and seen in others, the orbicular muscles are strongly contracted,
and tears sometimes flow freely down the cheeks. It has been suggested
to me that this may be due to irritating matter being injected into
the nostrils, and causing by reflex action the secretion of tears.
Accordingly I asked one of my informants, a surgeon, to attend to
the effects of retching when nothing was thrown up from the stomach;
and, by an odd coincidence, he himself suffered the next morning
from an attack of retching, and three days subsequently observed
a lady under a similar attack; and he is certain that in neither case
an atom of matter was ejected from the stomach; yet the orbicular
muscles were strongly contracted, and tears freely secreted.
I can also speak positively to the energetic contraction of these same
muscles round the eyes, and to the coincident free secretion of tears,