ILLUSTRATIONS IN THE TEXT 



FIGURE PAGE 



1. HVDROMEDUSA (GONIONEMUS VERTENs) I? 



2. DlAC.RAM OF THE BELL OF AURELIA AURITA, (AFTER GLAUS.) . iS 



3. EXPERIMENT IN DIVIDING A HYDROMEDUSA 19 



4. ARRANGEMENT FOR PRODUCING AUTOMATICALLY PULSATING AIR- 



BUBBLES 21 



5. DR. HARGITT'S EXPERIMENT .27 



6. DIAGRAM OF THE ASCIDIAN HEART ...... 28 



7. LOCALISING REFLEX IN TIAROPSIS INDICANS 31 



8. DIAGRAM FOR EXPLAINING THE LOCALISING REFLEX IN MEDUSAE 32 



9. CIONA INTESTINALIS 36 



10. THE ABILITY OF THE ACTINIANS TO DISCRIMINATE ... 49 



11. CONTINUATION OF THE EXPERIMENT IN FIG. 10 .... 50 



12. AN ACTINIAN (CERIANTHUS) WITH A NORMAL HEAD AND WITH 



AN ARTIFICIALLY PRODUCED HEAD 52 



13. AN ACTINIAN (CERIANTHUS) THAT HAD BEEN PLACED IN A TEST- 



TUBE, HEAD DOWN, REGAINING ITS NORMAL ORIENTATION . 55 



14. CERIANTHUS REGAINING ITS NORMAL ORIENTATION . . .57 



15. ACTINIAN THAT HAS BEEN FORCED BY GRAVITATION TO PUSH 



ITSELF THROUGH A WIRE NET THREE TlMES .... 59 



16. NERVOUS SYSTEM OF A STARFISH .... 61 



17. MECHANISM OF THE TURNING OF A STARFISH THAT HAS BEEN LAID 



ON ITS BACK 62 



18. Tin. SAME EXPERIMENT ON A STARFISH WHOSE NERVE-RING HAS 



BEEN SEVERED IN Two PLACES f>3 



19. GEOTROPIC REACTION OF CUCUMARIA CUCUMIS . .67 



ix 



