bars.  The jaws, tightly pressed, grind the teeth, and in some persons the delirium is carried so far that they bite to bleeding the shoulders their companions have imprudently abandoned to them.  This frantic state of epilepsy lasts but a short time, but it suffices to exhaust the forces of the organism, especially in man.  It is, I believe, Galen, who said:  ’Omne animal post coitum triste praeter mulierem gallumque.’"[107] Most of the elements that make up this typical picture of the state of coitus are not absolutely essential to that state, but they all come within the normal range of variation.  There can be no doubt that this range is considerable.  There would appear to be not only individual, but also racial, differences; there is a remarkable passage in Vatsyayana’s Kama Sutra describing the varying behavior of the women of different races in India under the stress of sexual excitement—­Dravidian women with difficulty attaining erethism, women of the Punjaub fond of being caressed with the tongue, women of Oude with impetuous desire and profuse flow of mucus, etc.—­and it is highly probable, Ploss and Bartels remark, that these characterizations are founded on exact observations.[108]

The various phenomena included in Roubaud’s description of the condition during coitus may all be directly or indirectly reduced to two groups:  the first circulatory and respiratory, the second motor.  It is necessary to consider both these aspects of the process of detumescence in somewhat greater detail, although while it is most convenient to discuss them separately, it must be borne in mind that they are not really separable; the circulatory phenomena are in large measure a by-product of the involuntary motor process.

With the approach of detumescence the respiration becomes shallow, rapid, and to some extent arrested.  This characteristic of the breathing during sexual excitement is well recognized; so that in, for instance, the Arabian Nights, it is commonly noted of women when gazing at beautiful youths whose love they desired, that they ceased breathing.[109] It may be added that exactly the same tendency to superficial and arrested respiration takes place whenever there is any intense mental concentration, as in severe intellectual work.[110]

The arrest of respiration tends to render the blood venous, and thus aids in stimulating the vasomotor centers, raising the blood-pressure in the body generally, and especially in the erectile tissues.  High blood-pressure is one of the most marked features of the state of detumescence.  The heart beats are stronger and quicker, the surface arteries are more visible, the conjunctivae become red.  The precise degree of blood-pressure attained during coitus has been most accurately ascertained in the dog.  In Bechterew’s laboratory in St. Petersburg a manometer was introduced into the central end of the carotid artery of a bitch; a male dog was then introduced,