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254 



STALK-EYED CRUSTACEA. 



whelmed to our eyes by the expansion of the red chromatoUasts under 



According to 



the influence of the darkness in which these animals hve 



Pouchet,* the piguients of the xanthic series (red, orange, and yellow) in 



Crustacea are contained in contractile anatomical elements, 



blasts, 



the chromato- 



tr 



J 

 1 



IE 



ii. 



4 J 



tt 



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while the blue pigment is never found in the substance of the 

 chromatoblasts, but is held in free solution. Pouchet found that living 

 prawns {Leander serrator) when placed in a vessel with a black bottom 

 always assumed a brownish red color, but if they were transferred to a 

 white-bottomed vessel they became yellowish, — the intrinsic color of their 

 tissues. Extirpation of the eyes of the prawn had the same elTcct as a black 

 bottom, specimens thus mutilated remaining permanently red. The change 

 from yellow to red was accomplished much more quickly than the reverse 

 change from red to yellow. In the latter case the change was efFected in 

 about twenty-four hours, during which the animal passed through a transi- 

 tory bright blue stage, — a phase of color not exhibited during the passage 

 from yellow to red. 



Le microscope expliquc cotte triple apparence. Quand Ics chromoblasles sout 

 contractus a I'etat splidrique, ils soiit trop petits pour faire uno imago perceptible sur 

 la rdtinc, et sont do nul effet. Des que I'animal est sur fond noir, los chroinoblastcs 

 so dilatent ; ils etendcnt do tous c8te8 dcs ramifications qui couvrent une grande sur- 

 face ; ils dcviennent porceptibles et modifient I'image rdtinicnne. L'animal, sous 

 cette influence, dcviendrait d'un rouge ou d'un rose franc, si uu autre pigment ne 

 venait rabattre la vive tcinte des chromoblastes. Mais, ^ mcsnre qu'ils Etendcnt leurs 

 ramifications sous rhjpodorme, on voit ce dernier tissu, h Icur voisinagc, prendre inie 

 belle nuance cobalt plus ou moins haute de ton. C'cst ce bleu qui sort do hruniture 

 au carmin des chromoblastes et donncnt au Palemon sa coulcur proprc [rouge 

 brunatrc] sur fond noir. Qnand Ics chromoblastes dilates se r^tractent de nouvcau, 

 ce bleu, qui s'est produit dans rhypodcrmc ct qui TimprSgnc, pcrsistc pendant six 

 a, sept hcurcs ct disparait progressivcmenfc " 



The prawn depicted on Plate H {Benlhcsieymiis tanneri) was brought up 

 from a depth of 860 fathoms and drawn as soon as it was taken from the 

 trawl. The general color is a deep blood-red or crimson, passing into 

 scarlet on the abdomen. The dorsal side of the first abdominal segment 

 is adorned with a large squarish spot of a deeper red than the rest of the 

 abdomen. This spot is repeated on the second, third, and fourth abdom- 



On the third and fourth segments the spot is bright cobalt 



inal segments. 



* Journ. dc TAnai. ct dc la Thyalol, YIIT. 401, 1872, 





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