PHYSIOLOGY. 



659 



a movement of the vocal cords tending to close 

 the glottis, then the diaphragm contracted so 

 as to press upon the upper surface of the 

 stomach, and at the same time the abdominal 

 walls contracted energetically, and a morsel of 

 food was thus thrown up into the mouth, any 

 excess of water in it being pressed out and 

 swallowed ; then the cud-chewing movements 

 began, and with them a copious flow of saliva 

 into the mouth ; and, finally, with a swallow- 

 ing movement, the masticated morsel was sent 

 back to the fourth stomach for complete di- 

 gestion. The size of the mass regurgitated was 

 determined by the sphincter muscles at the 

 cardiac opening of the paunch, these relaxing 

 at the beginning of the act, but closing again 

 when a small quantity had been forced out. The 

 whole series of movements was readily brought 

 about by electrical stimulation of the walls of 

 the paunch, or when this organ was mechani- 

 cally excited by distention with warm water 

 or by pressure with the hand. The flow of 

 saliva and the chewing movements followed in 

 regular order when food was expelled from 

 the paunch, even though the morsel did not 

 reach the mouth, which it was prevented from 

 doing in some cases by a division of the esoph- 

 agus. The author concludes that rumination 

 is a complex reflex action, the stimulus to 

 which is the distention of the walls of the 

 paunch by the accumulated food ; the amount 

 of pressure upon the wall being also, no doubt, 

 regulated by the motor nerves of the stomach. 

 Physiological Action of Drugs. Investigations, 

 including compounds of more than forty of the 

 elements, on the relations between the chemi- 

 cal constitution of substances and their physi- 

 ological action, have been made by Dr. James 

 Blake, of San Francisco. He has found a close 

 connection existing between the isomorphic 

 properties of various salts and their effects 

 when injected directly into the veins and ar- 

 teries. He has further been able to announce 

 the law that "among the salts of the metallic 

 elements the intensity of their physiological 

 action is connected with the atomic weight 

 of the element, so that when the elements are 

 arranged in isomorphous groups, the action of 

 the substances in the same group is a function 

 of the atomic weight ; the greater being the 

 atomic weight, the smaller is the quantity re- 

 quired to produce the same physiological ac- 

 tion." He has arranged ten isomorphous groups 

 of elements, concerning the physiological ac- 

 tion of which severally he has reached con- 

 clusions substantially as follow : Salts of the 

 soda group, in which are included lithia, soda, 

 potassa, rubidium, silver, caesium, gold, and 

 thallium, when injected into the veins in suffi- 

 ciently concentrated solutions to give rise to 

 any marked physiological reactions, kill by 

 arresting the passage of the blood through the 

 lungs, apparently by causing contraction of the 

 pulmonary arteries. When injected into the 

 arteries, the quantity required to kill is much 

 greater than when introduced into the veins. 



The salts of gold and silver cause contraction 

 of the systemic arteries as well as of the vessels 

 of the lungs. The action of the substances in 

 this group as a whole, except of the potash 

 salts, is to keep up the irritability of the heart. 

 On the nervous system their action is but slight. 

 Of the magnesia group including magne- 

 sia, manganese, iron in ferrous salts, nickel, 

 cobalt, copper, zinc, and cadmium the most 

 marked 'physiological effect in venous injec- 

 tions is suddenly to arrest the action of the 

 heart. Injected into the arteries, they gen- 

 erally arrest respiration before reaching the 

 heart in a sufficiently concentrated state to 

 stop its action. The effect on the nervous sys- 

 tem is well marked. Even in small quantities 

 they give rise to a state resembling catalepsy. 



The salts of lime, strontia, and baryta, con- 

 stituting the baryta group, injected into the 

 veins, destroy the irritability of the heart, ar- 

 resting its pulsation in diastole. When they 

 are injected into the arteries, the heart's pul- 

 sations are quickened and the pressure in the 

 arteries is slightly increased. Action on the 

 nervous system is not marked. 



Salts of the group including beryllium, alu- 

 mina, ferric iron, yttria, and cerium (Ce a O s ), 

 injected into the veins, cause contraction of 

 the pulmonary arteries, resulting in death if 

 the quantities are large, slowing of the action 

 of the heart, with decided vagus pulsations 

 when the quantities are smaller. Injected into 

 the arteries, the first effect is generally inhi- 

 bition of the heart's action, followed by rapid 

 rise in the pressure in the arteries. The direct 

 action of these salts on the muscles of the heart 

 is to increase their irritability. After the in- 

 jection respiration is often suspended for one 

 or .two minutes, and again goes on regularly, 

 but very slowly, and the action in the general 

 reflex functions of the medulla and spinal cord 

 is well marked. All the substances in this 

 group are very poisonous. 



The platinum and palladium salts, when in- 

 jected into the veins, act directly on the in- 

 trinsic nerves of the heart, slowing its action 

 with vagus pulsations and diminution of the 

 arterial pressure. When injected into the ar- 

 teries, the vagus center is immediately affected, 

 and the action of the heart is slowed. They 

 produce intermissions of respiration, which are 

 repeated till breathing stops for good. 



The salts of thoric and cerous oxide (CeO 2 ) 

 agree with the alumina group in acting prin- 

 cipally on the vagus and vaso-motor centers. 



The salts of lead, when introduced to the 

 blood, exert an action on the pulmonary ar- 

 teries and capillaries similar to that of the soda 

 salts ; and on the muscles an action analogous 

 to that of the baryta salts, whereby muscular 

 movements continue for many minutes after 

 death. The toxic activity of lead is much less 

 than that of either of the elements with which 

 its physiological reactions connect it. 



Phosphorus, arsenic, and antimony are all 

 distinguished by the absence of any well-marked 



