PHYSIOLOGY. 



655 



oated the results of investigations into the dif- 

 ferences that have been observed in the move- 

 ments in the blood-circulation of the colored 

 and of the colorless corpuscles. Among the 

 phenomena of the circulation to which he has 

 given special attention are those of the exist- 

 ence of two streams in the arteries and veins, 

 which are better seen in the arteries, the one 

 axial and the more rapid, the other peripheral 

 and slower; that the colored corpuscles float 

 exclusively in the axial stream, while a great 

 many, not all, of the leucocytes float in the 

 peripheral ; that the number of leucocytes in 

 the peripheral stream is greater in the veins 

 than in the arteries; that the motion of the 

 colored corpuscles is gliding, while that of the 

 colorless ones is rotating ; that in the veins the 

 colorless corpuscles have a tendency to stag- 

 nate when they get into the peripheral stream, 

 while the colored have not ; and that the capil- 

 laries have not any visible axial stream, and in 

 those which admit a single corpuscle only there 

 is a tendency, for the leucocytes more especial- 

 ly, but also for the colored corpuscles, to stag- 

 nate. Dr. Hamilton used artificial experimental 

 tubes and preparations in which the conditions 

 of density and gravity, etc., of the circulatory 

 system were reproduced as nearly as possible. 

 The phenomena of peripheral and axial streams 

 are results of friction, from which the water in 

 the middle of the tube being relatively free, 

 it moves more rapidly and directly than at the 

 peripheries, where it is retarded by the sides of 

 the vessel. On introducing solid spheres into 

 the liquid thus flowing through the tubes, Dr. 

 Hamilton found that the position they assumed 

 in the stream and their behavior in it were 

 largely matters of their specific gravity as com- 

 pared with that of the liquid plasma in which 

 they were floating. The colored corpuscles, 

 having almost exactly the specific gravity of 

 the plasma, assume their position in the center 

 and float with the central current. The color- 

 less corpuscles being specifically lighter than 

 the plasma, their tendency is to rise; hence 

 they come in contact with the vessel- wall more 

 than the others, where they are retarded at 

 the point of contact and consequently roll. 

 These conclusions were tested by other experi- 

 ments with blood and capillary tubes, in which 

 it was found that by altering the specific grav- 

 ity of the blood-plasma through a range of 

 something like 1,040 to 1,080, we can make 

 the colored blood-corpuscles float at any level. 

 The lower the specific gravity the more they 

 tend to come in contact with the bottom of the 

 tube, while the higher the specific gravity the 

 more they rise to the higher levels. The nearer 

 we approach the natural specific gravity of the 

 normal plasma, the more they occupy the axis 

 and the quicker they move. The conclusions 

 drawn by analogy from the artificial experi- 

 ments were thus confirmed and found applica- 

 ble to the actual circulation. Besides the situ- 

 ation occupied by the bodies suspended in the 

 tube, the experiments determined also that the 



ease with which any suspended bodies will cir- 

 culate depends (their size being appropriate to 

 that of the tube) upon the relationship of the 

 specific gravity of the bodies and that of the 

 liquid in which they are suspended. The more 

 they diverge in specific gravity from that of 

 the liquid, the more friction is caused, and the 

 more tendency there is to their becoming re- 

 tarded and finally arrested in their progress. 



Rhythmical contraction and dilatation of 

 the small blood-vessels, independently of the 

 action of the heart, have been observed by 

 Wharton in the veins of the bat's wing; by 

 Schiff in the arteries of the rabbit's ear ; by 

 Cohnheim and Gunning in the web and tongue 

 of the frog ; and by Ludwig and Brunton in 

 the arterial twigs of the subcutaneous con- 

 nective tissue. From these and other experi- 

 ments indicating similar properties, Dr. T. 

 Lauder Brunton infers that rhythmical con- 

 tractile power seems to be a quality common 

 to all the blood-vessels in the body, and in fact 

 to belong to involuntary muscular fiber gen- 

 erally; and an experiment by Luchsinger, in 

 which distinct pulsation could be observed in 

 the veins of a bat's wing when artificial circu- 

 lation was kept up, for twenty hours after 

 death, appears to show conclusively that it is 

 the involuntary muscular fiber composing the 

 walls of the vessels, and not the nervous sys- 

 tem, that has to do with it. Dr. Brunton has 

 made observations on rhythmical contraction 

 and dilatation of the capillaries, independently 

 of the heart and respiration, in man. They 

 were made in cases of marked aortic regurgi- 

 tation by observing the variations in width 

 and brightness shown by the red streak which 

 appears when the finger-nail is drawn across 

 the forehead. It is easy in this experiment to 

 observe, in addition to the visible pulse cor- 

 responding to the cardiac beat, a second 

 rhythm of contraction and dilatation corre- 

 sponding to the respiratory movements. 



In determining the velocity of the blood- 

 current in making the circuit of the body, Dr. 

 Smith calls attention to the inaccuracy of the 

 old experiments, in which the time elapsing be- 

 tween the injection of an iron salt into the 

 jugular vein, and its appearance in the jugular 

 on the other side of the neck, was made the 

 test. The inaccuracy arises from the fact that 

 different chemical substances in solution make 

 this circuit in very different periods. By his 

 method, defibrinated pigeon's blood is injected 

 into one jugular vein of an animal whose blood 

 is allowed to drop from the other jugular into 

 a series of watch-glasses placed in a circle upon 

 a table, which is revolved by clock-work. 

 Microscopic examination of blood thus col- 

 lected is made to determine in which watch- 

 flass the oval corpuscles of the pigeon's blood 

 rst appear ; then, knowing the rate at which 

 the table is turned, it is easy to estimate the 

 time taken by the pigeon's blood in passing 

 from one jugular to the other, in which pas- 

 sage it has probably traversed not only the 



