724 



PHYSIOLOGY. 



piration; and this, agrees with the fact that 

 breathing is always of the costal type when the 

 respiratory needs of ,the body are unusually 

 urgent. It appears also that the sura of the 

 vital capacities determined by movement of the 

 ribs and diaphragm separately is considerably in 

 excess of that which measures the extent of the 

 simultaneous action of all the muscles. Atten- 

 tion is called to a type of respiratory move- 

 ment related to the fact that the air in the 

 breathing apparatus increases in its content of 

 carbonic dioxide and loses oxygen progressively 

 from the external orifice to the lung alveoli ; and 

 the movements of respiration, so far as concerns 

 the demands of the body, simply cause a more 

 complete mixture of gases already in the lungs. 

 If the glottis be closed and such respiratory 

 movements be made as to stir together the gases 

 already contained in the air cavities, the physio- 

 logical result will be the same as that of genuine 

 respiration with open glottis. The respiratory 

 needs of the body may be thus fairly well satis- 

 fied for a considerable time without inhaling 

 fresh air. The alternate movements of the chest 

 and diaphragm, which take place as one of the 

 first symptoms of distress for want of air, have 

 their function thus explained. The simultane- 

 ous inspiratory and expiratory actions of the two 

 sets of muscles which take place under these cir- 

 cumstances are called complementary movements 

 of respiration. 



A second application of the experiments was 

 made to determine what relation, from a physio- 

 logical and an artistic point of view, the comple- 

 mentary movements of respiration may have to vo- 

 calization. The general conclusion drawn from 

 a preliminary inquiry is that, while the main 

 volume of the vocal blast is properly supplied by 

 the steady sweep of diaphragm and abdominal 

 muscles, the accent which gives life to song and 

 speech is accompanied and supported by a char- 

 acteristic play of chest and diaphragm in which 

 the rapid changes of the fundamental note of the 

 great thoracic resonator adjust it anew for every 

 note sent out from the vocal cords. 



The experiments of Fred Smith on the chem- 

 istry of respiration in the horse during rest and 

 work were tried with all the usual paces of the 

 animal. In the case of the different actions, the 

 experimental apparatus was applied instantly on 

 the end of the action, and held for twenty seconds. 

 Two hundred and fifty-one experiments were 

 made upon 35 horses. At rest the respirations 

 varied in number from 9 to 12 per minute, and 

 the quantity of air expired from 25 to 145 cubic 

 feet per hour, from 70 to 80 cubic feet per hour 

 representing a fair average. After walking the 

 mean amount of air expired was 133-55 cubic feet 

 per hour ; after trotting (nine miles per hour), 

 288 cubic feet per hour ; after cantering, largest 

 amount, 604. smallest amount, 231 cubic feet per 

 hour; after the gallop, mean amount, 849*09 

 cubic feet per hour. The tests were also applied 

 to the amounts of carbonic acid exhaled and of 

 oxygen absorbed. Some features of the author's 

 apparatus are criticised by Drs. N. Zuntz and C. 

 Lehmann, who, experimenting upon horses while 

 actually working in a treadmill apparatus con- 

 structed specially for the study, have obtained 

 values far greater in all the items than Mr. 

 Smith's. They further observe that the differ- 



ences in the numbers obtained by Mr. Smith in 

 individual experiments are much larger than 

 variations exhibited in their own experiments 

 when the work done by the horse was identical ; 

 and they find a harmony between the amounts 

 of carbonic acid produced by these animals and 

 the amount calculated on the basis of the food 

 given ; all of which they claim as in favor of 

 the superior accuracy of their larger values. Mr. 

 Smith replies that differences in the breeds of 

 the horses experimented with may have had 

 something to do with the differences in results. 



The effect of an increase of intercranial press- 

 ure or tension on the circulation and respiration 

 has been investigated by Walter Spencer and 

 Victor Horsley. The authors find that the 

 functions named are influenced through the 

 diminution in the physiological activity which 

 the increased pressure causes. A considerable 

 increase of the intercranial pressure was re- 

 quired to influence the heart ; it became slowed 

 and finally arrested. This happened more read- 

 ily after respiration had ceased, and required a 

 higher pressure to produce it when artificial res- 

 piration was employed, while division of both 

 vagus nerves abolished any slowing or arrest. 

 A primary rise of blood pressure was followed 

 by a fall distinct from that produced by the 

 slowing of the heart, and not necessarily accom- 

 panying it. The power of producing this effect 

 was easily lost. Respiration was likewise im- 

 paired and arrested. Its arrest reacted upon the 

 heart and the blood pressure upon it, so that 

 after the rise of blood pressure respiration oc- 

 curred, even though a much higher intracranial 

 pressure was maintained than had been sufficient 

 to arrest it when the blood pressure was lower. 

 The results are also noted of direct applications 

 of pressure to different portions of the heart. 



The statement of Bonders that the inhaling of 

 carbonic acid at the end of an expiration ma- 

 terially increases the depth of the ensuing ex- 

 piration, is confirmed by the experiments of Dr. 

 Zagari as described by Prof. Gad. This reflex 

 effect is not observed after section of the vagi, 

 and is not affected by section of the recurrent 

 laryngeals. It did not take place when a glass 

 tube was pushed down the trachea and one 

 bronchus, so as to protect those portions of the 

 air passages from the action of the gas, but it 

 reappeared on withdrawing the tube till its end 

 rested at the bifurcation of the bronchi. The 

 effect was observed when the carbonic acid was 

 diluted with 50 per cent, of air, but not upon 

 further dilution. Marshall Hall's theory of res- 

 piration receives no confirmation from these ex- 

 periments. 



Digestion. Of the results of his research in 

 the physiology of the salivary secretion upon 

 the connections of peripheral nerve cells with 

 the nerve fibers which run to the sublingual and 

 submaxillary glands, J. N. Langley lays espe- 

 cial stress on the conclusions that both the se- 

 cretory and vaso-dilator fibers of the chorda 

 tympani are connected with nerve cells. The 

 nerve cells on the course of the fibers to the sub- 

 lingual gland are scattered over the whole of the 

 gland forming a number of small ganglia; one 

 of these is the ganglion commonly called the 

 submaxillary ganglion. The real submaxillary 

 ganglion lies in the hilus of the gland, but a 



