854 SPECIAL PHYSIOLOGY. 



hold the nose with one hand, which would limit his powers of search 

 and prehension at the bottom of the sea ; moreover, if the nostrils are 

 not closed, the muscles of the glottis and of inspiration must be kept 

 incessantly strained, or an irresistible expiratory effort would take 

 place, and expel some air from the chest. With this protection on 

 the nose, however, the diver has only to keep the mouth closed ; the 

 inspiratory muscles are not required to act, and the contents of the 

 chest are mechanically retained. 



Persons who have been submerged for four or five minutes are rarely 

 restored to life, and sometimes, often owing, doubtlessly, to the en- 

 trance of water into the air-passages, persons who have been sub- 

 merged scarcely a minute cannot be resuscitated. 



A submergence of five minutes is almost certainly fatal to Man, still 

 recoveries have occasionally taken place after much longer periods, 

 even a quarter of an hour, and it is said after half an hour or more. 

 In such cases, however, it is believed that just before, or at the moment 

 of immersion, syncope, from some cause or other, has taken place. In 

 this condition, or in a state of trance, the heart beats feebly, or scarcely 

 at all, the respirations are weak and shallow, and life may be said to 

 be interrupted, or so feebly maintained that it may be continued as 

 well under the water as above it ; venous blood is not propelled through 

 the system, so that the nervous centres are not poisoned by carbonic 

 acid; and, unless the temperature of the water be very 'low, the 

 vitality of the respiratory nervous centres, of the muscles of respira- 

 tion, and especially of the heart, may be suspended, but not altogether 

 destroyed. Such a condition of syncope or fainting may be produced, 

 either by a severe blow causing concussion of the brain, by other phys- 

 ical shocks to the body, by sudden fright, or violent passion. For 

 these reasons, attempts at the resuscitation of apparently drowned per- 

 sons should always be resolutely persevered in, even under most unfa- 

 vorable circumstances. 



Certain methodical rules have been laid down, by means of so-called 

 artificial respiration, for the recovery of drowned persons ; and, with 

 the exception of such parts of those rules as relate to the removal of 

 water from the mouth and nostrils, and the replacing of cold and wet, 

 by warm dry clothing, similar instructions would apply to the recovery 

 of persons suffocated in brewers' vats, wells, and sewers, and also to 

 those aspkyxiated in the administration of ether or chloroform. In 

 the case of persons mechanically strangled or choked, the external or 

 internal cause of obstruction in the air-passages must, of course, be 

 first removed. The earlier rules, published by the Royal Humane So- 

 ciety, for the recovery of drowning persons, were improved by Dr. 

 Marshall Hall ; but the most simple and convenient are those of Dr. 

 Silvester, which have been incorporated with the present rules of that 

 society. 



