292 $ Usee I la n eo us . 



The little ditch in which I found PalmeUa vvrformis is some- 

 times filled with running or stagnant water, sometimes perfectly 

 dry. The metamorphoses undergone by the Alga 4 it contains en- 

 able them to adapt themselves to the different conditions presented 

 by their surounding medium. The presence of crystals of carbonate 

 of lime, indicating a great concentration of this calcareous salt in 

 the ambient nutritive fluid, might, according to the observations of 

 Famintzin, contribute to the disaggregation of the Confervoid Alga 

 into a PalmeUa. — Bull. Soc. Vaud. Set. Nat. xviiL p. 115; Bill. 

 Univ. January 15, 1883, Bull. Set. p. 109. 



On the Chromatophores of the Cephalopoda. By M. It. Blanchard. 



The author has investigated the chrotnatophores of Octopus 

 vulgaris, Loligo vulgaris, and Sepia officinalis in adult examples, 

 and of the last-named species in the young embryo. The results 

 obtained were identical throughout. 



Kolliker, in 1844 CEntwicklungsgesch. der Cephal opoden/ p. 71) 

 attributed the expansion and contraction of the chromatophores to 

 the contraction and relaxation of peculiar muscular fibres situated 

 near these pigment-cells, but having no connexion with the chroma- 

 tophores themselves; later writers (such as llailess, Keferstein, and 

 F. Eoll) have gone further, and described these muscles as. inserted 

 upon the enveloping membrane. In 1875 Harting (NiederL Archiv 

 fiir Zool. tome ii.) showed that these radiating fibres remain per- 

 fectly motionless, and that the play of the chromatophores was not 

 due to the contraction of any muscular fibres. He regarded the 

 radiating fibres, of which from twelve to twenty surround each 

 chromatophore, as so many nerve-terminations attached to the 

 enveloping membrane of the chromoblast by a clavate extremity 

 containing a nucleus. The membrane, he thought, was filled with 

 a transparent liquid, within which the denser coloured protoplasm 

 spread out and contracted under the influence of the nerves. 



The author agrees with Harting and (jiirod that there are no such 

 things as the radiating muscles ; but as regafds the opinion of the 

 former, he has found that there is no enveloping membrane : and with 

 it disappears the contained liquid. He says that the chromatophore 

 of the Cephalopoda does not differ at all in its general structure 

 from those of fishes, Batrachia, and especially Sauria (Chameleon) ; 

 it is a simple connective cell charged with pigment, and possessing 

 in the highest degree the faculty of pushing forth amoeboid processes 

 into the amorphous material which exists beneath the epidermis. 

 The chromatophore alone is active, and the surrounding tissues take 

 no part in the performance of its movements ; and the author com- 

 pares it to an Amoeba loaded with pigment, living its own life inde- 

 pendently of the skin in which it is imprisoned. 



This Amoeba, however, is under the influence of the nervous 

 system, as has been shown to be the case in the chameleon by the 

 experiments of Briicke, H. iJilne- Edwards, and Paul Bert, and in the 



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