674 



PHYSIOLOGY. 



The researches of Brucke and Lacken indi- 

 cated that contact with foreign bodies causes 

 blood to coagulate ; while Grunhagen found 

 that blood when received into glycerine, and so 

 long as it did not mix, remained liquid. A 

 reconciliation of these contradictory results 

 seems to have been found by Ernst Fresend, 

 whose comparative experiments with blood in 

 contact with substances of different characters 

 show that coagulation depends on adhesion ; 

 the lack of adhesion preventing it, while its 

 presence gives the impulse to the change. 



From experiments upon the eel's heart and 

 the skeletal muscles of the frog, S. Ringer and 

 D. W. Buxton conclude that contractions can 

 not be maintained when the heart is supplied 

 with a circulation composed of simple saline, 

 of saline plus potassium chloride, or saline plus 

 sodium bicarbonate, or saline plus both these 

 salts; that phosphate of calcium added to 

 saturation to saline can sustain contractility, 

 but leads to great delay of dilatation with per- 

 sistent spasm and fusion of the beats; that 

 these effects are completely obviated by the 

 addition of potassium chloride ; that we have 

 in phosphate of calcium saline with potassium 

 chloride an excellent circulating fluid capable 

 of maintaining the heart for several hours ; and 

 that calcium chloride solution is inferior to the 

 phosphate in its powers of supporting contrac- 

 tility. 



The heart of the toad-fish, Patrachm tau, 

 has been studied by Prof. T. Wesley Mills, with 

 especial reference to determining the order of 

 the beats and the effect of various drugs upon 

 it. The normal order of the beats is sinus, au- 

 ricle, venticle, but the heart of this fish is dis- 

 tinguished from that of all animals above it in 

 the scale of life by the great ease with which 

 its natural order of beat may be disturbed. Of 

 drugs, pilocarpine tends to slow the rhythm, 

 while atropine quickens it, and increases the 

 force of the beat. Sodium carbonate quickens 

 rhythm, diminishes diastolic relaxation, and 

 hardens cardiac excitability, but to a less ex- 

 tent than atropine. Potassium carbonate di- 

 minishes excitability, weakens the heart's ac- 

 tion, and tends to arrest it in diastole. Lactic 

 acid in five-per-cent. solution is a rapid poison, 

 while in solution of one per cent, it depresses 

 the heart and gradually kills it in diastole. Di- 

 gitaline produces gradually increasing systolic 

 contraction, while the diastolic relaxation gets 

 less and less till the heart is finally arrested in 

 most pronounced systolic tetanus. Nicotine 

 produces variable effects, from which the 

 heart has the power of recovering rapidly. 

 The principal action of veratria is on the dias- 

 tole, which it renders more sluggish, while the 

 effect on the systole is slight. The rhythm is 

 slowed, but want of harmony between the dif- 

 ferent parts of the heart and different fibers of 

 the same part is liable to manifest itself. Un- 

 diluted chloroform is a cardiac depressor, act- 

 ing most readily on the auricle proper, and 

 capable of arresting the heart in diastole. The 



organ has considerable ability to recover from 

 the effects of this agent. Acetate of strychnia 

 has the power of shortening the diastole, 

 lengthening the systole, and slowing the 

 rhythm. 



Experiments by Augustus D. "Waller show 

 that each beat of the human heart is accom- 

 panied by an electrical variation which is 

 proved, by the method of investigation adopt- 

 ed, to be physiological and not due to any 

 mechanical or accidental conditions. But the 

 character and direction of the variations are 

 not yet so clear as to enable the author to at- 

 tempt an interpretation of them. 



The distribution of the blood-vessels in the 

 retinae of mammals has been studied by James 

 W. Barrett with the aid of the hardened eyes 

 of men and children and of wild animals. The 

 term " internuclear layer " in the catalogued 

 arrangement of the layers of the retina was 

 found to be wanting in accurate definition, 

 and in many animals appeared susceptible of 

 further, more precise, division ; as in the ret- 

 ina of man and some other animals, it seems 

 to be divided into "fibrous" and "reticulat- 

 ed " layers. Blood-vessels were seen in the 

 outer reticular layer of the internuclear layer 

 or in the undivided internuclear layer of most 

 of the animals examined, and generally in the 

 inner part of the layer only ; but in no case 

 was a blood-vessel seen in the outer nuclear 

 layer of a mammalian retina or crossing the 

 membrane dividing the nerve from the epithe- 

 lial layers. The author's observations therefore 

 go to confirm the supposition that the epithe- 

 lial layers of the retina are extra-vascular. 

 The retina? of ruminants appear to be exceed- 

 ingly vascular. 



Respiration. The question whether an in- 

 creased absorption of oxygen takes place when 

 the tension is increased, has been investigated 

 by Dr. Lukjanow through experiments on 

 various animals exposed to an atmosphere 

 containing larger proportions of oxygen and of 

 higher pressure than the normal. The mean 

 result of all the experiments was a slight in- 

 crease, of four per cent, in volume, of oxygen 

 absorption. Dr. Herter, who presented the 

 subject before the Physiological Society of 

 Berlin, was of the opinion that this small in- 

 crease could not be regarded as a consequence 

 of increased oxygen tension, because, in indi- 

 vidual animals, the means of oxygen absorp- 

 tion sometimes fell below, and sometimes ex- 

 ceeded the normal amounts, and, further, be- 

 cause they did not vary proportionately with 

 the increased tension of the oxygen of the air. 

 The increase must be referred to other causes, 

 such as the movements of the animals during 

 the experiments. No increase of the tempera- 

 ture was observed under the increased pressure 

 of oxygen ; the conclusion was drawn that the 

 absorption of oxygen is not an ordinary com- 

 bustion process, and that the normal composi- 

 tion of the atmosphere contains the most suit 

 able percentage of oxygen. 



