510 



RAYMOND PEAKIi 



PAGE 



b. Crawl in J? Movement .... 548 



1. Direction . . . .550 



2. Stimuli which induce Crawlino: . . . 551 



c. Movement on the Surface Film . . . 552 

 (1. Relation of the Movements of Tiiclads to those of other 



Forms . . . . • 553 



TI. Non-locomotor Movements . . . 555 



a. Contraction of the Body . . . ' . 555 



b. Extension of the Body .... 556 



c. Rest . . . . .557 



i. Formation of Collections . . . 566 



d. The Effect of Operations on Movement . . 570 

 p. Eeactions to Stimuli ..... 576 



T. Reactions to Mechanical Stimuli . . . 576 



a. Methods . . . • .576 



b. Descrii)tion of Reactions .... 577 



1. Reactions to Stimuli applied to the Head Region . 577 



«. Reactions to Strong Stimuli . . 578 



j8. Reactions to Wc:ik Stimuli . . 582 



2. Reactions to Stimuli applied to the Middle Region of 



the Body . . . .588 



o. Reactions to Strong Stimuli . . 588 



jS. Reactions to Weak Stimuli . . 589 



S. Reactions to Stimuli applied to the Posterior Region 



of the Body . . . .592 



4. Reactions to Stimulation of the Ventral Surface . 594 



5. Reactions of Resting Specimens to Mechanical 



Stimuli . . . .595 



6. Reactions to Slimuli given by Operative Proce- 



dure ..... 595 



7. The Effect of Mechanical Hindrance to Movement . 597 



c. The General Features of the Reactions to Mechanical 



Stimuli . . . . .600 



f/. The Mechanism of the Reactions . . . 602 



1. The Relation of the Brain to the Reactions . 602 



2. The Neuro-muscular Mechanism . . 606 



e. Features in the General Behaviour of the Organism which 



the Reactions to Mechanical Stimuli explain . 619 



/. Summary . . . . .623 



II. Reactions to Food and Chemical Stimuli . . 623 



a. Food Reactions ..... 624 



1. Food Reactions of Specimens after Operations . 637 



2. Summary of Food Reactions , . . 640 



