Physiology. 
Mechanism of Tricuspid Valve..— Krehl^ publishes a careful 
and detailed account, illustrated by good figures, of the action of this 
valve during the whole cardiac cycle. 
Innervation of Renal Blood Vessels.— J. Rose Bradford's 
work* adds to our knowledge, hitherto defective, of this subject. Roy's 
oncometer was used and the tracing of the volume of the kidney was 
compared with that of the general blood pressure. The main conclu- 
sions are as follows : 
1. All renal vaso-motor fibres leave the spinal cord through the 
anterior roots, and although a few fibres may come out as high as the 
4th dorsal, it is not until the 6th dorsal is reached that they are found 
in any abundance. From the 6th dorsal to the 13th dorsal they are 
abundant; below this they are found in rapidly diminishing numbers, 
so that but little vaso-motorial effect is seen to follow the e 
the 3d and 4th lumbar nerves. 
2 . These renal vaso-motor fibres are of two kinds, 
and vaso-dilator. The former are, however, by far the best developed, 
so that unless special methods, such, for example, as slow stimulation, 
are used, it is rare to get clear evidence of vaso-dilatation on excitation 
of any given nerve. 
3. The kidney vessels receive their nerves from all the spinal nerves 
included in this extensive series, but most of the renal vaso-motor 
fibres are found in the nth, 12th, and 13th dorsal nerves. 
4. No evidence has been obtained of the existence of any vaso- 
constrictor fibres for the kidney vessels in the vagus nerve. The 
splanchnic nerve contains not only vaso-constrictor but also vaso- 
dilator fibres for the vessels of the abdominal viscera, and for the renal 
vessels amongst the rest. 
5. By reflex excitation of the renal nerves through the sciatic, inter- 
costal or vagus, active renal contraction is obtained : through the de- 
pressor, active expansion, which is, however, usually neutralized and 
changed into passive contraction by the great dilatation elsewhere ; 
through a posterior root, especially of the nth, 12th, and 13th, active 
expansion, due to the stimulation of afferent visceral nerve fibres. Oc- 
tasionally reflex excitation produces general dilatation, and then the 
