CHAP. V COLOUR-PHENOMENA IN WORMS 97 



The only detailed investigations on the pigments 

 of Turbellaria appear to be those of Moseley, who 

 made some observations on two species of Rhyncho- 

 demus found in New South Wales. Of these one 

 was blue and the other red, the two living together 

 under somewhat similar conditions. The blue 

 pigment was insoluble in alcohol, turned red with 

 acids, and then dissolved in alcohol ; alkali restored 

 the blue colour. This at once suggested that the 

 red pigment was due to an acid reaction in the tissues 

 of the red species, and was simply a modification of 

 the blue. Moseley could not, however, succeed in 

 turning the red pigment blue with alkali, and found 

 that it was insoluble in acidified alcohol. He was 

 forced therefore to the conclusion that the two 

 pigments are entirely different ; no further investiga- 

 tion seems to have been made on the subject. 



It is interesting to note that in spite of the 

 simplicity of the Turbellarians, the coloration is not 

 necessarily completely uniform, but may show an 

 arrangement into bands and spots. Thus the species 

 of Geoplana often show a dorsal stripe of green, 

 orange, or purple, while the rest of the body may 

 show spots of blue, brown, or yellow on a dull 

 ground. 



The pigments of the Nemertea have been even 

 more neglected than those of the Turbellaria, though 

 with less excuse. We quote the following eloquent 

 description of their colours from Professor M'Intosh's 

 monograph : — " The colours of many species of the 

 group are of such beauty as to attract even the 

 casual observer, while in this respect also they widely 

 deviate from their supposed allies the parasitic 



H 



