1884] Physiology. 837 
diac rhythm and augments the force of the auricular contractions, 
while stimulation of the vagus slows the rhythm and diminishes 
the strength of the auricular contractions.” 
Guided by these facts the author was successfully led to 
attempt to isolate the sympathetic nerve twigs which join the 
cranial vagus in the frog near its exit from the skull, and the fol- 
lowing are the physiological results obtained : 
“Stimulation of the sympathetic before its entrance into the 
combined ganglion of the sympathetic and vagus, produces purely 
augmentor (accelerator) effects. Stimulation of the vagus within 
_ the cranial cavity before its entrance into the ganglion, produces 
_ purely inhibitory effects.” 
___ The communication is of special value in removing a doubt as 
to whether the action of individual nerves is physiologically in- 
variable or capable of being altered under changed conditions. 
Jl. Physiology, Vol. v, No. 1. 
THE TIME TAKEN BY THE BLOOD IN MAKING THE CIRCUIT OF 
THE Bopy.—Dr, Smith, in describing a new method for deter- 
mining the velocity of the blood current, calls attention to the 
__-Maccuracy of the old experiments by which it was sought to find 
; the rate of circulation by measuring the time elapsing between 
l the injection of an iron salt into one jugular vein and its appear- 
ce in the jugular on the other side of the neck. Various 
4 chemical substances in solution make this circuit in very different 
Pe ods, because, apparently, of their different diffusibility. 
: According to the method now considered, de-fibrinated pigeon’s 
: i aio oo hen one 4a eee vein E an animal ymo Soo 
2 o drop from the other jugular into a series 0 - 
g placed in a circle upona able which is revolved by clock- 
‘ Work, Microscopic examination of the blood thus collected is 
1 aaa determine in which watch-glass the oval corpuscles of 
the Pigeon’s blood first appear ; then knowing the rate at which 
. table ts turned it is easy to estimate the time taken by the 7 
passage j lood in passing from one jugular to the other, s a 
but th it has probably traversed not only the heart and lungs, 
1 capillaries of the head as well. The mean of six experi- 
dirs. Sives the time of circulation in the dog as 17.5 seconds, 
time © Which the heart made 51.5 pulsations. In the rabbit the 
31 Of circulation was 11 seconds, during which there were 
aurea beats. When solid particles are injected into a egies 
this t as the blood, the heavier ones are carried at a faster rate 
the the lighter, because the former are more readily drawn into 
ao tly Moving axial current. Thus in the living blood-ves- 
tora! current, while the li ur chiefly in the 
OR S ghter leucocytes occ in 
Parl inert” layer. The author finds that very finely pijo 
Particles suspended in a fluid require twice as long to - 
