CAROTINOIDS IN INVERTEBRATES 165 



and describes the transformation of the blue aqueous solution into 

 "zoonerythriin 1 ." He says, in substance, that if a filtered blue aqueous 

 extract is treated with a drop of acid (H 2 S0 4 , HN0 3 , HC1, acetic or 

 picric), and then with a drop of strong KOH, NaOH or NH 4 OH, and 

 then with several drops of absolute alcohol, there is an instantaneous 

 color change of blue to red orange. On filtering, the filtrate is color- 

 less and the red-orange substance left on the filter gives all the prop- 

 erties of "zoonerythrine." Merejowsky describes a similar change 

 for a green water-soluble "astroviridine" which he extracted from 

 the Crustacea, Gebbia littoralis and Paloemon viridis. 



Miss Newbigin (1897) likewise obtained an aqueous solution of blue 

 pigment from the hypodermis of the lobster and the epidermis of the 

 fresh water crayfish by suspending scrapings from the shell of hypo- 

 dermis in 0.1 per cent HC1. She states, "This solution is first pink 

 but later turns blue on standing as the solution becomes neutral or 

 alkaline with the formation of CaCl 2 from the line of the shell. The 

 blue solution is very unstable. Heat (45 50 C.), acids, alcohol or 

 ether turn it pink instantly. The pink pigment is readily soluble in 

 alcohol or ether, and gives all the characters of crustaceorubin." An 

 observation that ammonia is always given off at the conversion of 

 blue into red suggested to Miss Newbigin that the compound of 

 lipochrome giving the blue color is an organic base. She points out 

 that it cannot be a simple ammonia compound because the alkali 

 compounds of the red pigment are red, not blue. 



It is clear that the true explanation of the character of these inter- 

 esting chromogens has not yet been discovered. One cannot help but 

 wonder whether there may be an analogy between these phenomena 

 and blue colloidal gold. The sensitiveness of the blue solution to 

 reagents which are known to aggregate colloidal particles and the 

 precipitation of chromolipoid which occurs following the use of these 

 reagents is certainly strongly suggestive of a colloidal phenomenon. 

 The stabilizer of the suspensoid may well be a basic ammonia-con- 

 taining substance extracted from the tissues with water. 



Carotinoids in Echinoderms 



The most familiar of the animals included under this group are the 

 Asteroids, or star-fishes; the Ophiuroids, or brittle stars; the Echi- 

 noids, or sea urchins; the Crinoids, or sea lilies; and the Holothuroids, 

 or sea cucumbers. The various colors shown by these interesting 



