566 Prof. C. 8. Sherrington. On Reciprocal [Nov. 3, 
vy. Frey.* He investigated the effect on the venous flow from the sub- 
maxillary gland of simultaneous stimulation of the vaso-constrictor (cervical 
sympathetic) and the vaso-dilatator (chorda tympant) nerves. The dilatating 
influence of the chorda proved to be completely overpowered by the constricting 
effect of the sympathetic during combined stimulation of the two. But 
on discontinuing the combined stimulation there ensued from the vein a 
markedly excessive blood-flow, 7.e., a marked chorda action ensued as an 
after-effect. The action of the sympathetic had, therefore, not destroyed 
the action of the concurrently excited chorda, it had only postponed its 
appearing. v. Frey, with his customary clearness, wrotet: “the antagonism 
between constrictor and dilatator has not as its basis a simple summing of 
two forces which act in opposite direction at the same point of application.” 
The sympathetic prevails entirely for the time being as regards the surface 
effect, but the chorda nevertheless develops with regular course the change 
characteristic of its action, and does so “in some part of the excitable 
apparatus protected from the attack of the sympathetic: only in some other 
place do the actions of the two collide.” 
Some years later Heidenhain,§ discussing the acceleration of pulse-rate, 
which in the frog follows discontinuance of a stimulation of the vagus-trunk, 
attributed it to accelerans fibres commingled with the inhibitory in the vagus- 
trunk, and with them excited by the stimulus applied. He then went on to 
suggest that inhibitory actions fall into two classes which should be clearly 
distinguished one from the other. He argued that in one class the inhibitory 
process antagonises the excitatory process by decreasing or suppressing its 
actual occurrence. Whereas in a second class the inhibitory process, 
without actually lessening, or indeed altering, the excitatory process, simply 
prevents the latter from, for the time being, getting access to and affecting 
the organ of its destination, the organ which, but for the inhibition, it would 
reach and affect. To this second class of inhibitions he relegated the vagus 
action on the heart and its interference with the accelerator on that organ. 
As another example of this second class, he cited similarly the opposition 
between sympathetic and chorda on the vessels of the submaxillary gland. 
This explanation of inhibition brought forward by Heidenhain as satis- 
fying the cases which he terms inhibitions “of the second class” resembles 
the hypothesis earlier offered by Rosenthal.|| Rosenthal, after making his 
*  Arbeiten a. d. physiol. Anstalt z. Leipzig,’ 1876. 
t+ Ibid. . 
t Ibid. 
§ ‘ Pfliiger’s Archiv,’ vol. 27, p. 283, 1882. 
|| ‘ Die Athembewegungen u. ihre Beziehungen z. N. Vagus,’ Berlin, 1862. 
