MARINE BIOLOGICAL STATION AT PORT ERIN. 195 



II. One reddish-brown specimen, dredged amongst red 

 algae on August 19th, was put that afternoon in a glass 

 jar with green algae {Enter omorpha) on a white background 

 in the sun. On the morning of the 21st it was almost 

 colourless, having merely a pale grey-green tint, and was 

 quite inconspicuous. When examined in a watch glass 

 under the microscope the integument was seen to be 

 almost quite transparent, the pale grey-green muscles 

 showing through distinctly, and the chromatophores or 

 pigment spots being reduced to minute rounded, very 

 rarely branched or stellate, dots which were all of a dark 

 red-brown colour, but from their small size produced 

 little effect upon the general tint of the body. When put 

 back amongst the red weeds it was originally taken from 

 this specimen now looked pale green and conspicuous. 



III. One red, one brown, and two speckled-red speci- 

 mens dredged amongst red and brown sea-weeds in Bay 

 Fine were put on September 7th at 10 a.m. into a glass jar 

 with green algae, in the sun. At 8 p.m. the brown one 

 was much paler, being a mixture of gamboge and pale 

 neutral tints, while the other three had not undergone 

 much change. On September 8th at 10 a.m. (i.e., after 

 24 hours in all) the brown one had become distinctly 

 green and was quite inconspicuous, while the red and 

 speckled ones, although not green, had become much less 

 conspicuous by the w^hole body being very transparent, and 

 the red markings very much paler than they had been — 

 looking as if they had been almost washed out. 



Of the four possible alternatives stated in our last report 

 (p. 36) I now think that the 2nd, 3rd, and 4th are all parts 

 of the true explanation of the state of affairs — that is, that 

 there are no permanent varieties, but the young when they 

 first settle down upon the sand or sea-weeds have, what- 

 ever the colour inherited from their parents may be, great 



