636 



PHYSIOLOGY. 



variation in different persons and at different 

 times, and, if so, whether there is any connec- 

 tion between variations of alkalinity and the 

 di astatic action of saliva. More than fifty spe- 

 cimens of the saliva of fourteen persons were 

 examined. The average alkalinity of the sam- 

 ples expressed in the form of sodium carbon- 

 ate was -080 per cent. The average diastatic 

 action of fifty-four samples expressed in the 

 percentage of sugar formed from the starch 

 was 42-82 per cent. An examination of the 

 individual results obtained showed several in- 

 teresting facts, which may be summarized as 

 follows: 1. Saliva from different individuals 

 may show a constant difference in alkalinity, 

 although in the majority of cases the alkalinity 

 varies only within narrow limits ; 2. Saliva se- 

 creted by the same individual at different times 

 has within certain limits a constant degree of 

 alkalinity ; 3. While saliva from different indi- 

 viduals shows in several cases a decided and 

 constant difference in alkalinity, there is no cor- 

 responding difference in diastatic action which 

 is at all constant. We are thus forced to the 

 conclusion that the variations of alkalinity are 

 within too narrow limits to exercise any ap- 

 preciable influence on the diastatic action of 

 the saliva. 



B6champ has investigated the origin of the 

 power possessed by human saliva of saccharify- 

 ing starch-paste a power which the saliva of 

 many animals, including even such herbivores 

 as the horse, has not. He concludes that it is 

 not due, as some have thought, to chance germs 

 which have entered the mouth from the at- 

 mosphere, but to a special ferment more active 

 than diastase, and that it is produced by the 

 action on the pure secreted saliva of specific 

 microscopic organisms living in the salivary 

 glands and in the mouth-cavity of man. The 

 pure parotid saliva of horse or dog does not 

 convert starch-paste into copper-oxide-reduc- 

 iug substances, nor does it acquire this power 

 when exposed to the air, or when gently warmed 

 with scrapings from the tongues of those an- 

 imals; but it becomes very efficacious when 

 scrapings from the inside of the human mouth 

 are added to it. 



E. Jessen has made investigations respect- 

 ing the time required to digest meat and milk 

 prepared in different ways : 1. With artificial 

 gastric juice. Of twenty-five grammes of beef 

 in each condition, at the end of twenty-four 

 hours : 5 grammes of the raw, from 9* to 9f 

 grammes of the half-cooked, and from 17 to 18 

 grammes of the well-done beef remained undis- 

 solved. 2. In the stomach of a dog. The raw 

 meat was also digested more quickly than 

 boiled or roasted meat, the time required for 

 raw beef being from 5'3 to 5'5 hours. 3. Ex- 

 periments were made upon man by introducing 

 100 grammes of meat and 300 c. c. of water 

 into an empty stomach, pumping out the con- 

 tents of the stomach after a time, and examin- 

 ing them with a microscope. The time required 

 for complete digestion was as follows : 



Hours. 



Eaw beef, shaved fine 



Half-done boiled beef, shaved flue . 2* 



Well-done boiled beef, shaved fine 3 



Half-done roaeted, shaved fine 8 



Well-done roasted, shaved fine 4 



Eaw mutton 2 



Eaw veal 2 } 



Kaw pork 3 



In the experiments with milk, a quantity 

 was given, the amount of nitrogen in which 

 would correspond with that contained in 100 

 grammes of beef. This with cow's milk was 602 

 cubic centimetres. That quantity of the raw 

 milk was digested in 3| hours ; of boiled milk 

 in 4 hours ; of sour milk in 3 hours ; 675 c. c. 

 of skimmed cow's milk were digested in 3 

 hours ; 656 c. c. of raw goat's milk in 3 hours. 



The Physiology of Voice. Prof. T. Wesley 

 Mills, of McGill University, has published the 

 results of examinations which he has made with 

 the laryngoscope and tested by autolaryngo- 

 scopy upon certain controverted questions of 

 the physiology of the voice. The questions em- 

 brace the functions of the epiglottis in changes 

 of pitch and of quality, the influence of the 

 trachea and of the supra-glottic chambers on 

 pitch, the falsetto voice, and the registers of 

 the singing voice. On the first point Mr. Wal- 

 ton has maintained, in a paper published in 

 1878, that "the epiglottis was seen to take 

 different positions in changes of pitch, quality, 

 and intensity." Prof. Mills, remarking that this 

 author and others have made the mistake of 

 considering the movements of the epiglottis as 

 essential when they are only incidental, con- 

 cludes from his own observations that "the 

 epiglottis may act like a resonator, and proba- 

 bly is one in some degree ; that by its move- 

 ments it is a modifier of the quality of sounds, 

 but not appreciably of their pitch ; but that 

 the question as to how far the mere presence 

 of the epiglottis independently of its particu- 

 lar movements may influence these qualities of 

 sound is not as yet determined in the human 

 subject." Concerning the influence of the 

 trachea on pitch, "it is a matter of common- 

 est observation, that above a certain point in 

 the scale (which latter varies with sex, age, 

 and the individual), the larynx rises or falls 

 according as the pitch is above or below this 

 fixed point, which has been named the ' station- 

 note.' " It appears from the experiments that, 

 while the breath-pressure is almost if not quite 

 sufficient of itself to account for the rise of the 

 larynx and trachea, it does not explain their 

 fall below the position for the " station-note " ; 

 and for the efficient action of the arytenoid 

 and cricoid cartilages in particular, and to 

 effect a state of support and tension generally 

 in the larynx, certain muscles, including the 

 thyro-hyoid, the palatopharyngeus, and the in- 

 ferior constrictor, act in harmony. Helmholtz 

 gives no favor to the view that the supra- 

 glottic air-chambers can alter materially the 

 tones of the vocal cords. Notwithstanding 

 this authority, and a few experiments that are 

 cited as bearing apparently against his view, 



