154 PROTOPLASM PERFORMS 



the needful rest. J. Ranke is inclined to give the whole causa- 

 tion of fatigue to the accumulation of fatigue- stuffs^and little or 

 none to the over consumption and modification of the proto- 

 plasm. But I cannot agree to this, as fatigue, after over- 

 stimulation, is universal in all living functions, and especially 

 those of the nervous system, while we have few proofs of accumu- 

 lation of fatigue-stuffs. Besides, we know that when one kind 

 of stimulus has ceased to act, another will do so certainly not 

 from removing fatigue-stuffs. This harmonizes with the theory 

 that storing up is partly a simple growth of the protoplasm 

 whose decomposition is the source of the nerve force which 

 does muscular work, although there is a possible intermediate 

 chemical stage here ; still in all vital action the same vigour 

 and freshness is felt after repose. 



It is certainly noteworthy that a veteran experi- 

 mental physiologist like Voit should have the con- 

 clusion forced upon him, that muscle-work force, fat, 

 and milk are all, even in herbivorous animals, produced 

 by the decomposition of nitrogenous matter, and it is 

 30 far in harmony with the hypothesis of Fletcher,* 



* Dr. Fletcher (" Kudiments," &c., p. 108), after setting aside all 

 the theories of active elongation, reviews under six beads all the theories 

 of muscular contraction up to that time (1836), and concludes that the 

 most probable physical cause was the zigzag bending of the fibre, though 

 he rejects the hypothesis then tacked to it, that these bendings occurred 

 where a nerve loop passed round the fibre, and that the drawing was 

 caused by galvanic force sent by the nerve trunk. It is curious how 

 nearly Beale comes back to this, but at that time, the electro motor force 

 of galvanism was hardly known, and its conditions were not practically 

 iinderstood. Fletcher did not attempt to explain how he vital was 

 connected with the physical action. He says, " But, at the same time, 

 it must be continually kept in mind that there is still a wide, unoccu- 

 pied gap between simple irritation or the perception of a stimulus by a 

 muscle, and the assumption by its fibres of this zigzag direction as a 

 consequence of it." Nevertheless, this irritability is not inherent in the 

 fibre itself, but in the ganglionic nervous matter [protoplasm], inter- 

 woven with it, for in accounting for the essentiality of a supply of 

 blood to contraction, he says, " we must remember that it is by the 

 blood that the "nutrition of the limb is maintained, that its ganglionio 

 nervous tissue ceases in this case [tying the arteries] to be renewed in. 

 proportion as it is exhausted, and that there is consequently, after a time, 

 a cessation of irritability a necessary condition of muscular contrac- 

 tion" (117). 



