644 F. W. GAMBLE AND f. W. KEliBJ.K. 



central nervous system, and to that extent directly to light, 

 the pigments flowing into the branches from the centre, was 

 shown by cutting off appendages and making camera draw- 

 ings of a selected pigment spot. In one case the antennal 

 scale of a greenish prawn was cutoff, and a "chromatophore^' 

 carefully observed and drawn at short intervals. Twenty- 

 three minutes after the first drawing, the red and yellow 

 pigments had considerably expanded and penetrated into 

 the branches. In another case, PI. 36, fig. 36, a chromato- 

 phore was chosen from a prawn which was undoubtedly dead 

 after the first sketch was made ; the heart had ceased to beat 

 and the scaphognathite had stopped. Thirty-five minutes 

 afterwards, when the last sketch was made, the red and yellow 

 pigments were still actively spreading into the branches. 

 To make the crucial test of the direct power of response of a 

 " chromatophore " it should of course be completely severed 

 from all its nervous connections. This we have not yet done, 

 and consequently the results of the observations just quoted 

 cannot be regarded as definite proof of a direct response of 

 the chromatophoric pigments to changed light conditions. 



We employed several methods in attempting to render the 

 eyes functionless without causing shock. First, we tried to 

 render the cornea opaque by means of a mixture containing 

 Indian ink, which when dry is insoluble in sea water, but the 

 difficulty in maintaining the respiratoi'y current whilst allow- 

 ing the cornea to dry, and the uncertainty that light is 

 totally cut off from the retina, made us abandon this method. 

 We succeeded better by painting the eyes either with a 

 solution of collodion in ether, or with silver nitrate, and the 

 results thus obtained were confirmed in animals blinded 

 either by snipping off the eyes near the base of the eye- 

 stalks, or by pinching the optic ganglia with fine forceps. 



Different specimens of Hippolyte varians exhibit curi- 

 ously different degrees of shock under the operation. Noc- 

 turnes, for example, either remain motionless and strongly 

 bent, moving erratically if at all, or immediately find their 

 legs and exhibit little outward sign of discomfort. Ampu- 



