2IO PHYSIOLOGY OF THE INVERTEBRATA. 



the Coelenterates is by means of the ectodermic lining, for 

 this lining is very largely impregnated with respiratory 

 and other pigments, as shown by Prof. Moseley * and Dr. 



MacMunn-t 



The respiratory pigments are capable of existing in a state 

 of oxidation and reduction, and no doubt play an important 

 part in the function of respiration. 



Professor Moseley discovered a pigment called poly- 

 perythrin in various Ccelenterates, and Dr. MacMunn has 

 carefully examined the brown colouring matter of jelly-fishes, 

 and various pigments in the Actinia:. 



In Chrysaora hysocella a brown pigment is present in 

 ^' the radiating triangular areas on the upper surface of the 

 umbrella, and in dark patches, thirty-two in number, all 

 round the margin of the disc, also in the tentacles ; l)ut in 

 ■each of these situations it possesses the same properties. It 

 also occurs dotted on the surface of the umbrella between 

 the triangular pigmented areas. Microscopically, it occurs 

 in granules, and is limited to the surface ; these granules are 

 yellowish in colour under a high power." Dr. MacMunn 

 could not extract the brown pigment with alcohol, ether, 

 chloroform, alcohol and sulphuric acid, and alcohol and 

 potassium hydroxide. But he obtained an extract by allow- 

 ing portions of Chrysaora to stand, " the sea-water contained 

 in the tissues dissolved the pigment, forming an orange- 

 brown solution, showing a broad dark band at the blue end 

 of the green. When more pigment went into solution, the 

 fluid became a dark brown colour. Boiled in fresh and sea- 

 water the colour went into solution, but showed no bands 

 except the shading at the blue end of the green. A deep 

 layer of this solution only transmitted red and some green. 

 Ammonia and caustic potash precipitated the colouring 



* Quarterly Journal of Microscopical ihciety, vol. 17 ; and Journal of 

 Phijsio'ogy, vols. 7 and S. 



t Quarterly Journal of Microscopical Science, vol. 30 ; and Journal of 

 Marine Biological Association, 1889. 



