246 Physiologie der Zellen, Gewebe und Organe. 



nal cord, or of the posterior roots central to tlieir ganglia, does not influence 

 the vasodilatation. Section of the posterior roots peripheral to their ganglia of 

 origin does not Interrupt the vasodilatation until degeneration of the peripheral 

 parts of the fibres takes place. After degeneration the effect is abolished. The 

 afferent sensory posterior root fibres must be assumed to undergo a peripheral 

 bifurcation, one limb passing to a sensory end-organ in the skin the other pass- 

 ing to the bloodvessels in neighbouring regions. Irritation of the end organs 

 causes a nerve impulse to pass up one limb and down the other — an "axon- 

 reflex". The identity of the vaso-dilator fibres with the afferent posterior root 

 fibres, asserted by Bayliss in inOl, receives streng support from this work. 



Mines. 



646) Adrian, E. D., Wedensky Inhibition in relation to the "all-or-none " 

 principle in nerve. In: Journ. of Physiol. , Bd. XLVI, S. 384, 1913. 



The Wedensky Inhibition has been considered an objection to the all-or-none 

 principle in nerve. A series of strong Stimuli applied to a nerve may fail to excite 

 Ihe muscle, while a series of weak Stimuli, at the same frequency excite it. An 

 explanation of this fact, based on the all-or-none principle is given. The strong 

 Stimuli discharge more frequent waves of excitatipn than the weak Stimuli. Each 

 wave of excitation, when these are discharged at a slower rate, is stronger than 

 when they are discharged at a greater rate, because the recovery of the tissue 

 is more complete. The stronger waves are able to pass the neuro-muscular junc- 

 tion and to excite the muscle: the weaker waves cannot. 



Cooling a nerve at a point between the electrodes and the muscle increases 

 the least interval for muscular summation but does not alter the strength of 

 Stimulus needed to produce it. The refractory period set up by a strong second 

 Stimulus which falls too early to give a summated contraction may inhibit a third 

 Stimulus following soon after the second. 



The "all-or-none" relation between disturbance and Stimulus holds good for 

 refractory as well as for normal tissue. Mines. 



647) Lucas, K., The effect of alcohol on the excitation, conduction 

 and recovery processes in nerve. In: Journ. of Physiol., Bd. XLVI, S. 470, 

 1913. 



In a nerve treated with 5% alcohol in part of its course the impairment 

 of conduction and the increase of threshold current- strength in the narcotised 

 region follow a parallel course. Thus conductivity and excitability are affected 

 at the same time. 



Alcohol increases the least interval at which two Stimuli applied to the 

 nerve can cause muscular summation: this is not due to a prolonged refractory 

 period but to the nerve conducting with a decrem ent. 



The rate of conduction in a nerve is much slowed by alcohol at a stage at 

 which the rate of recovery is not slowed. This suggests that the recovery process 

 which is responsible for the refractory period is a process different from the 

 disturbance which is the basis of propagation of the nervous impulse. Mines. 



648) Dale, Dorothy and Mines, 0. R., The influence of nerve Stimulation 

 on the electrocardiogram. In: Journ. of Ph3'siol., Bd. XLVI, S. 318, 1913. 



Stimulation of the intracranial vagus in the frog produces different effects 

 on the electrocardiogram according to the degree of slowing of the rhythm. 

 In the absence of slowing, vagal Stimulation lengtheus the A — V interval and 



