NONPHOTIC RECEPTORS IN LOWXR FORMS 



383 



the horizontal axis and, in addition, i) yields adapting 

 impulses during movements, which increase in fre- 

 quency if the movement is carried out towards the 

 position of the maximal static stimulation and decrease 

 abruptly during movement away from this position. 

 A third system of receptors responds to angular ac- 

 celeration around every axis of the body. It shows a 

 tonic discharge which is independent of the position 

 when position is constant. This tonic discharge re- 

 mains even after removal of the statolith. The response 

 consists of a burst at the onset of rostrum-down, side- 

 down, or contralateral horizontal rotation, followed 

 by a depression at the termination of these move- 

 ments. The opposite movements result in a reversed 

 response sequence. The adaptation of the permanent 

 discharge to the resting value is completed in less than 

 I sec. This shows a striking similarity between the 

 basic principles of the mode of function of the crusta- 

 cean statocyst and the static apparatus of the verte- 



brates studied by Lowenstein (79) and von Hoist 

 (134); in both cases the sine law is obeyed; the ade- 

 quate stimulus is bending of the hairs; stimulus and 

 reaction have a linear relationship; and the sensory 

 epithelium emits a tonic impulse stream which is 

 modified by the bending of the hairs. A loss of the 

 tonic impulses on one side is compensated. This 

 ability is important as the statocysts have to be sup- 

 plied with statoliths from the outside after each molt, 

 at least in some species. In this procedure it is not 

 always possible to obtain statoliths of the same weight. 

 Orientation to gravity occurs in many cases without 

 the help of statocysts, as is the case in insects accord- 

 ing to Mittelstaedt (86), Pringle (96) and Schneider 

 (114), but the eyes often play an important role in 

 this adjustment (116). 



Professor Autrum's chapter was translated from the Ger- 

 man by Dr. and Mrs. Otto Scherbaum, Department of Zo- 

 ology, University of California at Los Angeles. — Ed. 



.S. J. mar. hiol. A. V. K. 31 : 277, 

 S. Puhhl. slaz. tool. Napoli 25: 94, 



REFERENCES 



1. .'\lexandrovvicz, J. S. Quart. J. Mkrosc. Sc. 92: 163, 1951. 



2. .\lexandrowicz, J. S. Quart. J. Microsc. Sc. 93: 315, 

 ■952- 



3. Alexandrowicz, J. 



'952- 



4. Alexandrowicz, J. 



'953- 



5. Alexandrowicz, J. S. J. mar. hiol. A. U. K. 35: 129, 



1956- 



6. .-Klverdes, F. AV«f Bahnpn in der Lehre vom Verhalten der 

 niederen Organismrn. Berlin: Springer, 1922. 



7. .'^utrum, H. ^tsckr. vergleick. Physiol. 23: 332, 1936. 



8. .\utrum, H. ^Ischr. vergleich. Physiol. 28: 326, 1940. 



9. Autrum, H. ^tschr. vergleich. Physiol. 28: 580, 1941. 



10. .^UTRUM, H. .Uaturivissensckaften 30: 69, 1942. 



11. .^UTRUM, H. Biol. Z^ntrathl. 63; 209, 1943. 



12. AuTRUM, H. Naturwissenschajten 39: 290, 1952. 



13. AuTRUM, H. Ann. Inst. .Nat. Rech. .igron. Ser. C. Ann. Epiphyt. 



6: 338, 195,5- 



14. .Autrum, H. Exper. Cell. Res. In press. 



15. Autrum, H. a.nd VV. Schneider, ^tschr. vergleick. Physiol. 

 31: 77, 1948. 



16. Barber, S. J. Exper. Zool. 131: 51, 1956. 



17. Bauer, L. ^tschr. vergleich. Physiol. 26: 107, 1938. 



18. Blattner, H. Arch. Protistenk. 53: 253, 1926. 



19. Boistel, J. and E. Coraboeuf. Compt. rend. Soc. de biol. 

 147: 1 1 72, 1953. 



20. Bullock, T. H. Biol. Rev. 30: 311, 1955. 



21. Bullock, T. H. and R. B. Cowles. .Science 115: 541, 



1952- 



22. Burke, \V. J. Exper. Biol. 31 : 127, 1954. 



23. Burkhardt, D. Ergebn. Biol. 20: 27, 1958. 



24. Burkhardt, D. and G. Schneider, ^tschr. Naturjorsch. 

 12b: 139, 1957. 



25. Busnel, R. G. (editor), .inn. Inst. .Nat. Rech. Agron. Ser. C. 

 .■Inn. Epiphyt., vol. 6, 1955. 



26. Cohen, M. J. J. Physiol. 130: 9, 1955. 



27. Cohen, M. J., Y. Katsuki and T. H. Bullock. Ex- 

 perienliag: 434, 1953. 



28. Copland, M. J. Exper. ^ool. 25: 177, 1918. 



29. Danisch, F. ^tschr. allg. Physiol. 19: 133, 1921. 



30. Dethier, V. G. In: Iruect Physiology, edited by K. D. 

 Roeder. New York: Wiley, 1953, p. 544. 



31. Dethier, V. G. Ann. New Tork Acad. Sc. 58: 139, 1954. 



32. Dethier, V. G. Quart. Rev. Biol. 30: 348, 1955. 



33. Dethier, V. G. and L. E. Chadvmck. Physiol. Rev. 28: 

 220, 1948. 



34. Dijkgr.'\af, S. Experientia 11 : 407, 1955. 



35. Eggers, F. Die stiJtJUhrenden Sinnesorgane. Zool. Bausteine, 

 Bd.2. Berlin: Borntraeger, 1928. 



36. Ewer, R. F. Proc. .^ool. Soc. 117: 365, 1947. 



37. Evzaguirre, C. and S. Kuffler. J. Gen. Physiol. 39: 87, 



1955- 



38. Evzaguirre, C. .\nd S. Kuffler. J. Gen. Physiol. 39: 



121, 1955- 



39. Fernandez-Mor.'\n, H. .Nature, London 177: 742, 1956. 



40. FiNLAYSON, L. H. AND O. Lovvenstein. .Nature, London 

 176: 1031, 1955. 



41. Florey, E. ^tschr. Naturjorsch. lib: 504, 1956. 



42. Florey, E. and E. Florey. J. Gen. Physiol. 39: 69, 1955. 



43. Frings, H. AND B. L. Cox. Biol. Bull. 107: 360, 1954. 



44. Frings, H. and M. Frinos. Am. Midland .\atural. 41: 

 602, 1949. 



45. Frings, H. a.nd B. R. O'Neal. J. Exper. ^ool- ^o'i- 61, 

 1946. 



46. Gerhardt, H. Zool- Jahrb., Abt. allg. ^ool- Physiol. 63: 



558, 1953- 



47. Goldsmith, T. H. and D. E. Philpott. J. Biophys.& 



Biochem. Cytol. 3: 429, 1957. 



48. Grabowski, C. T. and V. G. Dethier. J. Morphol. 94: 

 I, 1954- 



