I 



Miscellaneous. 293 



Crustacea and fishes by G. Pouchet, while Paul Bert has proved it iu 

 the cuttlefish. The connexion of the chromatophores with the nerves 

 has also been proved anatomically by Leydig in Lacerta agiUa, and 

 by S. Ehrmann in the frog ( Sitzungsber . Akad. Wiss. Wien, lxxxiv. 

 Abth. ;J, p. 165), Nevertheless, according to the author, the radiating 

 > fibres observed in the Cephalopoda are not, as supposed by Halting, 



nerve-terminations, but careful investigation showed them to be 

 simple fibres of connective tissue having no connexion with the 

 chromatophores. The phenomena presented by the chromatophores 

 are thus identical wherever these organs have been observed. — 

 Comptes Rendus, March 5, 1883, p. 655. 



On a Flagellate Infuwrian, ectoparasitic on Fishes, 



13y M. L. P. HENlfBGUT. 



; In 1876 M. Fouquet (Arch, de Zool. Exper. tome v.) made known 



a curious disease which almost every year attacks the trout bred in 

 the piscieultural basins of the College de Prance. About July an 

 epidemic breaks out, which carries off a great number of young fry 

 hatched during the winter, and is caused by a singular ciliated 

 Infusorian, Ichthyophthirius maltifilii, Fouquet, which lives para- 

 sitically upon the epidermis of the trout and of some other fish, 

 producing an inflammation of the skin. 



This year the young fry of the trout, when hatched about three 

 weeks, and before they had entirely absorbed the umbilical vesicle, 

 were decimated by a new malady, also due to a parasitic Infusorian. 

 When portions of epidermis from a dying fish are examined under the 

 microscope, their whole surface is found to be covered with small 

 bodies implanted upon the epidermic cells, and so closely applied to 

 each other that they do not allow the cells to be seen. These are 

 flagellate Infusorians, which may be studied when they become de- 



I taehed from the epidermis. Their form is different according as 



J they are in repose or in motion. 



When fixed upon the epidermis they appear to be small pyriform 

 cells, 0*02 millim. long and 001 millim. wide, with the larger end 



< free and the attenuated one attached to the epidermic cell. The 



body of the Infusorian is traversed by a clear longitudinal line 

 dividing it into two unsym metrical parts ; this line represents a 

 groove in which is lodged a long flagellum, passing the larger end. 

 Towards the middle there is a nucleus formed by a small, central, 

 clear mass, surrounded by a ring of refractive substance. This 

 nucleus is coloured by carmine and methyl-green. In the larger 

 end there is a eon tractile vacuole. 



When the animal quits the cell to which it was attached, it opens 



I in the line of the clear groove, and its anterior part spreads out ; it 



then presents the form of a little basin resembling the shell of a 



f Haliotis. At the middle of one margin are inserted three flagella of 



unequal length, which describe a curve with the concavity inwards 

 and then become free towards the anterior extremity of the body. 



t 





