-32- 



dlagraaed above^ Inthis way <pand d will be coordinated before 

 b though b and the neighboring raya ay be ;oore active in their 

 coordination than o and d because they receive stimulation 

 throu^i the rin : fro;.; both directions simultaneously. 



Now with the negative # response, conditions are different 



# The negative response has been described by Loeb (1900) 

 in terms cf observations by Norman (1900) as a result of the 

 retraction of tube feet on the harshly stimulated ray and a 

 consequent determination of the direction of the negative 

 responses by a "parallellogrim of forces" exerted by the other 

 rays, each, hypothetioally, as I take it, continuing, during the 

 negative rotation to pull in its ewn direction. It is -eil icnown 

 from the -/ork of l-tomanos, Preyer, Jannings, Mangold, Cole and 

 others tjiat all normal locomotion is brought about by the cooper- 

 ation of all of the tube feet stepping in one direction and not 

 the divergent pulls of the various ra s, which as w have seen 

 results in autotomy. 



in certain respects. Assuming that the harsh stimulus is given 



at b. The p*tk olLJEtttraaUoa JU1 w a* above ( but the Way 

 the coordination impulse spreads is tmtz identical with that 



|X 



diagrammed in fig. 2 so that o_ and d. become oocrdinated before 

 b, which is the location of the stimulation. 



Appearances seem to indicate that just after the retraction 

 following such, a negative stimulation, the tube feet on the 

 far side of the animal show a definite increase in activity. 



