158 E. LUCILE MOORE. 



locomotion is made possible. It had been generally believed 

 that only the crawling movement is accomplished through muscu- 

 lar contractions, and that gliding results chiefly from the beating 

 of ventral cilia; but Stringer (8) has shown that when muscular 

 activity is entirely checked locomotion does not occur, even 

 though the cilia are beating vigorously; and she concludes that 

 the "locomotion of planarians is essentially a muscular act in 

 which the cilia play no necessary part." 



Although the influence of adrenin upon the muscular con- 

 tractility of Planaria cannot be exactly homologized with that 

 upon vertebrate muscle, it is well to bear in mind the results of 

 these investigations. Oliver, and Schafer (7) report both a 

 greater and a more prolonged contraction of the gastrocnemius 

 in frogs as the result of adrenin injection, and also an increase 

 in muscular activity following administration of the extract by 

 mouth. Takajasu (9), however, working upon isolated muscle, 

 obtained ]ust the opposite effect. He found that the curve of 

 contraction in skeletal muscle, immersed in solutions of adrenin, 

 varying from I : 500,000 to I : 5,000, becomes successively lower 

 and of shorter duration, although there occurs a preliminary 

 period during which the contractions are slightly prolonged. 

 Gruber (3 and 4) has obtained interesting results with muscle 

 preparations in Avhich fatigue has been induced either electrically 

 or chemically. In these cases, adrenin, instead of causing a still 

 further lowering of the fatigue curve, really produces a rapid 

 recovery of the normal irritability of the muscle. Unlike Oliver 

 and Schafer, however, he reports no improvement in muscles 

 not fatigued. These investigators, it is evident, have employed 

 various means of introducing the extract, and have worked 

 upon both entire animals and isolated muscle. With planarians, 

 injection is impracticable, and the immersion of isolated muscle 

 altogether impossible; but by placing entire individuals in solu- 

 tions of adrenin, a combination of the methods of immersion and 

 feeding is obtained. 



The experiments here described were carried out upon Planaria 

 doratocephala, and Planaria velata. The worms were placed in 

 large ringer bowls, containing spring water, and kept in the 

 laboratory at as nearly constant temperature as possible. Food 



