286 W. J. CROZIER AND LESLIE B. ARI^Y 



repeated proddings of the gill crown, but relatively slight taps of 

 adjacent plumes will produce this effect under strychnine. The 

 'rhinophores' are not retracted under these circumstances; 

 whereas, if the 'rhinophores' themselves are touched, the gill 

 plumes do contract. 



In some individuals the 'rhinophores' were found to retract 

 noticeably, but not completely, when a bit of graphite or the end 

 of a glass rod or of an aluminum wire was brought near them 

 (within 2 to 3 mm., but not touching). Presumably this repre- 

 sents a heightened tactile irritability such as that seen in some 

 teleosts (Crozier, '18 c) after the removal of the eyes (i.e., when 

 the central reflex interference of optic impulses has been re- 



Fig. 6 Outline of Chromodoris to show gill-crown reaction under strychnine. 



moved). This type of irritability is not apparent in the non- 

 strychninized animal. 



After one hour, the dorsum is still wrinkled, but the animal 

 attempts to creep, usually falling over to one side after such an 

 attempt has endured for two to three minutes. The main body is 

 no longer forcibly contracted, but usually assumes a gentle spiral 

 form about the long axis, the head pointing downward on one 

 side, the 'tail' of the foot pointing upward and to the opposite 

 side; the surface of the foot is for the most part longitudinally 

 folded. Touching a 'rhinophore' causes both it and its mate to 

 retract; sometimes the opposite 'rhinophore' contracts before the 

 stimulated one, and usually the gill plumes contract also. The 

 lightest touch applied to a tentacle causes the homolateral 

 'rhinophore' to be fully retracted. When a 'rhinophoral' collar 

 is touched, it contracts, sphincter-wise, so quickly and so forcibly, 



