CAROTINOIDS IN THE VERTEBRATES 147 



de Merejowski, and in addition failed to show any absorption bands. 

 Krukenberg (1882e) later 1'ouiul the same pi.ument in the skin of the 

 goldfish, Cyprinus auratus and Cyprinus Carpio and (1882n) in the 

 skin of Mullus barbatiis. The red lipochrome in the latter iish, and 

 that which Krukenberg and Wagner (1885) extracted from the red 

 salmon muscle, yielded a pigment on saponification which showed the 

 single absorption band at F of Kiihne's rhodophane. It will be remem- 

 bered that Krukenberg found the same pigment in the feathers of 

 certain birds. MacMunn (see Cunningham and MacMunn, 1883) 

 later found it in a number of other fishes. In color, the pigment 

 resembles carotin most closely. Its relation to this pigment should be 

 determined. 



Krukenberg (1882e, n) first noted the yellow pigments in fishes, 

 extracting them from Cyprinus carpio, where they were present in the 

 skin along with the red chromolipoid, and from the skin of Barbus 

 fluviatilis, Muraena Helena, Belone rostrata, Scorpoena scrofa, where 

 they existed free from red pigment, and from Mullus barbatus, which 

 contained the red pigment, as already noted. The absorption spectra 

 of these pigments show their carotinoid nature, but it is difficult to 

 decide whether carotin or xanthophyll is the predominating pigment, 

 in view of the possibility that both types of carotinoid were present in 

 the solutions. 



The much more extensive observations of MacMunn (Cunningham 

 and MacMunn, 1893) on the chromolipoids of the skins of a number 

 of other species of fishes, which are accompanied by measurements 

 of the absorption bands in ether, chloroform and carbon disulfide, are 

 somewhat more instructive. A comparison of the data with known 

 measurements of the absorption bands of the carotinoids leads to the 

 following tentative conclusions: Carotin is the chief carotinoid in the 

 skin of the Flounder (Pleuronectes flesus), the Plaice (P. platessa), 

 the Dab (P. limanda), the Merry Sole (P. microcephalus) , of Solea 

 variegata, and of the Smelt (Osmerus eperlanus) ; xanthophyll is the 

 chief carotinoid in the skin of Amoglossus megastoma, Trig la cuculus, 

 Trigla hirundo, the Mackerel (Scomber scombrus), Syngnathus acus, 

 Siphonostoma typhle, CLupea narengus, Artherina presbyter, the John 

 Dorey (Zeus jaber) and the fifteen spined Stickleback (Gasterosteus 

 spinachia) ; both carotin and xanthophyll are found in Coitus bubalis, 

 and the banded Pipe Fish (Nerophis oequoreus) ; a pigment whose 

 spectra strongly resembled lycopin is the cause of the skin pigment 

 of the goldfish, Cirassius auratus. 



