Fractional Activity in Mammalian Reflex Phenomena. 133 



But in 1902 Gotch* showed that the electric organ of Malapterurus, which 

 is served by a single efferent fibre, as compared with that of Torpedo, which is 

 served by many fibres, has a much smaller range of reactions to reflex 

 excitation. He yet states that within very restricted limits the organ shock 

 is slightly augmented when an effective stimulus applied to its nerve is 

 increased in intensity. He also notes that the initial shock reflexly evoked 

 is variable in intensity, but he states that a considerable factor in this 

 variation of intensity is probably fatigue of the nerve endings in the organ. 



There is, however, some evidence which seems to show that the efferent 

 nerve fibre and the effector organ (skeletal muscle; when stimulated 

 artificially by faradic shocks may respond in an " all or nothing " manner to 

 the peripheral stimulus. 



In 1905 Keith Lucasf showed that when the exciting current which is 

 applied to the skeletal muscle of the frog is gradually increased in strength 

 the contraction of that muscle increases, not pari passu, but in abrupt steps. 



Four years later the same investigator showed^ that in the frog's cutaneus 

 dorsi muscle, there is an " all or nothing " contraction of the muscle fibres in 

 response to stimulation of the efferent nerve fibres — submaximal contraction 

 of the whole muscle being due to a maximal contraction of less than the 

 whole number of constituent muscle fibres. 



Veszi, in 1911,§ made a curious observation which seems to throw doubt 

 upon the " all or nothing " phenomenon in reflex conduction. He found, in 

 the de-afferented frog, that in the state of strychnine poisoning there is an 

 all or nothing " contraction of gastrocnemius in response to stimulation of 

 the cut afferent roots. A threshold stimulus evokes a maximum muscular 

 response. But when this has fatigued by repetition of stimulation, a stronger 

 stimulus again gives a maximum response. 



In the following year the same observer || came to the conclusion that the 

 fresh amphibian efferent nerve-fibres follow the " all or nothing " rule ; but 

 that when fatigued the value of the excitatory process varies with the value 

 of the exciting stimulus. 



Slightly more recently Adrian IT has investigated this question. He finds 

 that a propagated disturbance in the efferent nerve fibres of amphibian nerve 

 which has been reduced in magnitude by passing through a region of 



* ' Journ. Physiol.,' 1902, vol. 28, p. 395. 



t ' Journ. Physiol.,' 1905, vol. 33, p. 125. 



X 'Journ. Physiol.,' 1909, vol. 38, p. 113. 



§ 'Zeitschr. fur allgem. Physiol.,' 1911, vol. 12, p. 358. 



|| 'Zeitschr. fur allgem. Physiol.,' 1912, vol. 13, p. 321. 



IT ' Journ. Physiol.,' 1912, vol. 45, p. 389. 



