1910.] PHOTOPnOIlES OF UECArOD CRUSTACEA. 647 



^'e7'(/estes in the first cellular layer and in Acanthephyra in the lens 

 itself. 



There is reason to believe that this pigment is closely allied to, 

 if not identical with, that found in the Lobster. When the 

 photophore is placed in absolute alcohol the blue colour soon 

 becomes bright red, and the same reaction instantaneously appears 

 when it is boiled in a drop of water. If the lens of Acanthephyra 

 be dissected out and treated with strong sulphuric or nitric acid 

 the colour at once changes to red, and immediately afterwards 

 turns to a dull greenish blue of a much less distinct colour than 

 that originally present. The greenish-blue tone appears to fade 

 away a little later, but the concluding stages of the reaction are 

 somewhat obscured owing to the burning of the tissue by the 

 acid. 



The red pigment which gives the familiar colonizing to Nephrops 

 and to the lobster, when boiled, is known to be one of the lipo- 

 chromes or fatty pigments, called by Moseley crustaceoruhin, 

 associated with a small quantity of yellow pigment, known as 

 hepatochrome, which appears to be derived from the liver. The 

 investigations of Krukenbei-g * and of Miss Newbigin f seem to 

 show that the unstable blue-black pigment or Upochromogen which 

 occurs in the lobster is a compound of the red lipochrome with a 

 complex organic base. The blue colour is turned red by any 

 reagent which alteis the form of the proteid, and the red pigment, 

 extracted and dried, gives with strong acids a bi'illiant but 

 evanescent blue reaction. 



The photophores are unfortunately so minute that it is not 

 possible to extract a solution of the pigment ; but the reaction 

 mentioned above, which was obtained by the addition of acid to 

 the lens of Acanthephyra^ furnishes fairly sa tisf actoiy evidence of 

 the nature of the pigment J. The acid bi'eaks up the proteid and 

 at once converts the blue l\j)Ochromoyen into the red lipochrome, 

 and this is immediately followed by the characteristic blue re- 

 action which this pigment gives in the presence of an acid. The 

 tissues burn and become brown under the influence of the reagent, 

 and the rapid evanescence of the blue tint, which is characteristic 

 in the case of dry extracted pigment, is in consequence somewhat 

 masked. 



It has not been possible to test the blue pigment in the photo- 

 phores of Sergestes as fully as has been done in the case of 



* Krakenberg, Vergleich. Plivsiol. Studien, lite Keihe, 3te Aliteil., 1882, 

 pp. 02-107. 



t Newbidn, ' .louinal of Physiology,' vol. xxi. 1897, p. 237. 



X The following obseivations on tlie red colouring-niiitter of Arant/iephi/ra may 

 bo mentioned here. An ether extract of the pigment gave a bright yellow solution, 

 which en evaporation yielded an oily rod extract. On the addition of strong nitric 

 acid a bright, but rapidly evanescent, blue reaction was obtained which was folIo\yed 

 by the separation of the red matter from the oily yellow pigment, the lattr-r turning 

 adull green. Thi> result is iiractically identical with that obtained by Miss New- 

 bigin with the extracted pigments of Xephrnps. The red colouring which tuni.s 

 blue under the influence of the acid is the lipochrome, cvustaccornbiu, while the 

 oily yellow pigment is liepatochrome. 



