136 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



ceased, I made no visits to Menemsha from June 22 until July 16, when I found about 

 a dozen lobsters in the car, where tbey had been imprisoned from two to three weeks. 

 They were without exception of a brilliant blue color, and were very conspicuous 

 when placed with other lobsters recently taken in the Sound. They were all old-shell 

 females, most of which had hatched their eggs and were approaching their molting 

 time. All the green pigment of the shell had become light cobalt-blue, which, inter- 

 spersed with the usual Naples yellow tints, gave them a very striking appearance. 



According to the observations of MacMuun (132), the coloring of the skin of the 

 lobster (Astacus gammarus) and crayfish (Potamobius fluviatilis) is due to the presence 

 of chromogens, which are converted on very slight provocation, as by dehydration, 

 oxidation, or some molecular change, into a red lipochrome, resembling rhodophan. 

 Everyone is familiar with the wonderful change of color which the adult lobster under- 

 goes when boiled, 1 and according to MacMunn the beautiful blue pigment of the larval 

 lobster is converted by alcohol into a true lipochrome. 



Alcohol quickly converts the chromogens in the lobster's shell into lipochromes, 

 and dissolves them at the same time. This is well seen in recently molted lobsters, 

 where the colors are very brilliant. When placed in alcohol, the soft-shelled lobster is 

 first reddened, and then in a short time completely bleached, while a lobster with a 

 hard shell treated in the same way will retain some of its color for a long time, if not 

 indefinitely. The same changes are seen when the dark-green eggs are treated with 

 alcohol or boiling water. 



The lipochromes are pigments of a very wide distribution in the living world, 

 occurring in green leaves, in yellow flowers and fruits, and it is said that the ver- 

 tebrate retina, " egg-yolks of different species of animals, the yellow, green, or red 

 pigmented integuments of various invertebrates and vertebrates from fishes to birds, 

 owe their coloration, with few exceptions, to dissolved, granular, or diffusely distributed 

 lipochromes." (132, p. 95.) 



Lipochromogens are found in a natural state in the gastric glands, blood, soft skin 

 (as the blue prismatic cyano-crystals, which are reddened by alcohol or by boiling), and 

 in the exoskeleton of Crustacea. MacMunn is of the opinion that they are " built up in 

 the digestive gland and carried in the blood current to be deposited in other parts of the 

 body." (132, p. 62.) If this is true, it would not be remarkable if the color of the animal 

 were affected by the nature of its food, yet this does not seem to be often the case. 



The following substantive variations have been met with: (1) Blue lobsters, in 

 which the prevailing color is blue ; (2) red lobsters, which are pure red or reddish-yellow ; 

 (3) cream-colored lobsters, characterized by the almost entire absence of color; (4) we 

 should also add black lobsters, to include possible cases of melanism, where the colors 

 are extremely dark. A specimen of this kind was reported to me at Beal Island, near 

 West Jonesport, Maine, where a fisherman recently captured, in 3 fathoms of water 

 among the eelgrass, a lobster about 6 or 7 inches long with moderately hard shell and 

 almost jet-black. He supposed at first that it was covered with coal tar. It did not 

 appear to be preparing to molt. Malard (133) speaks of meeting with cases of melanism 

 in crabs, where in consequence of a lesion of the skin the crab becomes entirely black — 

 "charbonne," as the sailors describe it. 



■In France the lobster, Astacus gammarus, is said to be called the "red cardinal of the sea," and 

 the Norwegian lobster, Nethrops norvegicus, I am informed by Dr. Lonnberg, is called by the fishermen 

 in Sweden Eejsar h ummer, or emperor lobster, on account of its color and spines. 



