RESPIRATION 259 



statements to the contrary in ancient and modern books (for instance, 

 the story of the child that was gilded to play the part of an angel at 

 the coronation of a mediaeval pope, but died before the ceremony 

 began), the whole of the human skin may be coated with an im- 

 permeable varnish without any ill effects. The entire surface of the 

 body of a patient with cutaneous disease was covered with tar, and 

 kept covered for ten days. There was not the least disturbance of 

 any normal function (Senator). The serious effects of varnishing 

 the skin in animals are due, not to retention of poisonous sub- 

 stances, but to increased heat loss. Varnishing is not so rapidly 

 harmful in large animals like dogs, as in rabbits, which have a 

 relatively great surface and a delicate skin. The danger of wide- 

 spread superficial burns is well known. But it is not due to 

 diminished excretion by the skin, for death occurs when large 

 cutaneous areas remain uninjured. The patient nearly always dies 

 when a quarter of the whole skin is burnt ; yet the remaining three- 

 quarters may surely be considered capable, from all analogy, of 

 making up the loss by increased activity. One kidney is enough to 

 eliminate the products of the nitrogenous metabolism of the whole 

 body. It is difficult to see why the excretion of the trifling amount 

 of solid matter in the perspiration should be interfered with by the 

 loss of 25 per cent, of the sweat-glands. The real explanation of 

 the serious effects of extensive superficial burns is perhaps the ex- 

 cessive irritation of the sensory nerves, which may lead to changes 

 in the nervous centres, or reflexly in other organs. Some observers 

 have supposed that the chemical changes in the damaged tissue, 

 for example, in the blood-corpuscles, may be the cause of death 

 (Hunter), and others that it may be due to the transudation of lymph 

 at the injured part, and the consequent increase in the concentration 

 of the blood. 



Voice and Speech. 



Voice. Sounds of various kinds are frequently produced 

 by the movements of animals as a whole, or of individual 

 organs. The muscular sound, the sounds of the heart and 

 of respiration, we have already had to speak of. Such 

 sounds may be considered as purely accidental as the foot- 

 fall of a man or the buzzing of a fly. The wings of an insect 

 beat the air, not to cause sound, but to produce motion ; 

 the respiratory murmur is a mere indication that air is 

 finding its way into the lungs, it is in no way related to the 

 oxidation of the blood in the pulmonary capillaries. But in 

 many of the higher animals mechanisms exist which are 

 specially devoted to the utterance of sounds as their prime 

 and proper end. In man the voice-producing mechanism 

 consists of a triple series of tubes and chambers : (i) The 



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