CONTKACTION-REMAINDER. 



483 



Fig. 330. 



Lower curve is the normal muscle-curve (frog), upper one of the 



same muscle with veratrin (Stirling). 



wards lengthened. The gastrocnemius of a frog supplied by blood containing soda contracts 

 more rapidly (Griitzner). Kunkel is of opinion that muscular poisons act by controlling the 

 imbibition of water by the sarcous substance. As muscular contraction depends on imbibition 

 ( 297, II.), the form of the contraction of the poisoned muscle will depend upon the altered 

 condition of imbibition produced by the drug. 



[Veratrin. If a frog be poisoned with veratrin, and then be made to spring, it does so 

 rapidly, but w r hen it alights again the hind legs are extended, and they are only drawn up after 

 a time. Thus, rapid and powerful contraction, with slow and prolonged relaxation, are the 

 character of the movements. In a muscle poisoned with veratrin, the ascent is quick enough, 

 but it remains contracted for a long time, so that this condition has been called "contracture." 

 A single stimulation may 

 cause a contraction lasting 

 five to fifteen seconds, ac- 

 cording to circumstances (fig. 

 330). Brunton and Cash 

 find that cold has a marked 

 effect on the action of veratrin 

 in fact, its effect may be 

 permanently destroyed by 

 exposure to extremes of heat 

 or cold. The muscle-curve 

 of a brainless frog cooled 

 artificially, and then poison- 

 ed by veratrin, occasionally 

 gives no indications of the 

 action of the poison until its 

 temperature is raised, and 

 this is not due to non-absorption of the poison. Cold, therefore, abolishes or lessens the con- 

 tracture peculiar to a veratrin-curve. Similar results are obtained with salts of barium, and to 

 a less degree by those of strontium and calcium [Brunton and Cash).] 



Smooth Muscles. The muscle-curve of smooth or non-striped muscles is similar 

 to that of the striped muscles, but the duration of the contraction is visibly much 

 longer, and there are other points of difference. Some muscles stand midway 

 between these two, at least as far as the duration of their contractions is con- 

 cerned. 



The "red" muscles of rabbits, the muscles of the tortoise, the adductors of the common 

 mussel, and the heart, all react in a similar manner. 



Contraction-Remainder. A contracted muscle assumes its original length only 

 when it is extended by sufficient traction, e.g., by means of a weight. Otherwise, 

 the muscle may remain partially shortened for a long time. This condition has 

 been called "contracture" (Tiegel), or, better, contraction-remainder (Hermann). 

 This condition is most marked in muscles that have been previously subjected to 

 strong, direct stimulation, and are greatly fatigued, which are distinctly acid, and 

 ready to pass into rigor mortis, or in muscles excised from animals poisoned with 

 veratrin (fig. 330). 



Rapidity of Muscular Contraction. In man, single muscular movements can 

 be executed with great rapidity. The time-relations of such movements can be 

 ascertained by inscribing the movements upon a smoked glass plate attached to a 

 tuning-fork. Fig. 328, II, represents the most rapid voluntary movements that 

 Landois could execute, as, e.g., in writing the letters n, n, and every contraction is 

 equal to about 3*5 vibrations (1 vibration = 0*01613 second) = 0*0564 second. In 

 III, the right arm was tetanised, in which case 2' to 2*5 vibrations occur = 0*0323 

 to 0*0403 second. 



V. Kries found that a simple muscular twitch, caused by a single induction shock, 

 is shorter than a momentary voluntary single movement. If the thickening caused 

 by a single voluntary contraction of a muscle be registered directly, the curve 

 shows that the contraction within the muscle lasts longer than the duration of the 

 movement produced in the passive motor apparatus itself. This paradoxical 

 phenomenon is due to the fact that, shortly after the primary voluntary muscular 



