Show Laughter a Series of Barks Laughing is barking say the scientists sci-entists The neck and head arc thrown back while a series of short barks aro emitted from tho throat However musical tho barks may be hey are barks The laugh begins with a sudden and violent contraction of the muscles of tho chest and abdomen ab-domen But instead of opening to let the air pass out of the lungs the vocal cords approach each other and hold It back But they are not strong enough to exercise such opposition for more than an Instant njul tho air which Is under pressure promptly escapes As If does so It makes the vocal cords vibrato vi-brato producing tho bark This obstruction and liberation of tho air expelled from tho lungs repeats Itself again and again at Intervals of a quarter of a second Thcr are thus in a hearty laugh four barks a second and If continued they go on at that rate as long as tho air reserve In the lungs holds out The empty lungs must then fill themselves and this Interval In-terval Is marked by a quick gasp for breath after which tho barks aro renewed re-newed Tho barks occur In series with gasps for breath at intervals When laughter Is violent tho entire body participates Tho upper part of tho trunk bends and straightens Itself alternately or sways to right and loft Tho foot stamp on tho floor while the hands aro pressed upon tho loins to moderate the painful spasm |