334 Glironicles of Science. [April, 



rations have led him to regard as acoustic organs certain hairs npon 

 the surface of the Crustacea, which present the same structure as the 

 hairs connected with the otolites. They are especially numerous in 

 those species, or in larvae, which have no internal auditory organs, and 

 are renewed at each moult, Their structure is much more complex 

 than the other hairs of the surface, which latter are wholly devoid of 

 any nervous cord. Supposing that each auditory hair was capable of 

 being thrown into vibration by a determinate note, he subjected the 

 matter to experiment, and found that on sounding different notes of 

 the gamut certain hairs became indistinct by reason of powerful 

 vibrations, while the neighbouring hairs remained perfectly still, or 

 could only be made to vibrate by other notes. 



M. Jourdain has investigated the eyes of the common starfish, and 

 finds that they are more highly developed than is commonly supposed. 

 Of the two fundamental types of the organ of vision, viz. eidoscopic 

 eyes, which furnish images, and photoscopic eyes, which only are fitted 

 for giving a general sensation of light and darkness, he gives reason 

 to believe that in Uraster rubens there is a specialization of function 

 which no doubt represents the highest type of organization of photo- 

 scopic eyes. Eidoscopic eyes are found in the Mollusca, Insecta, and 

 Crustacea., and are connected with an expansion of a nerve of special 

 sense, upon which luminous rays are isolated. The photoscopic eye 

 is associated, in its simplest form, with blackish or reddish pigment, 

 of definite structure, in connection with the nervous system, or only 

 with the sarcodic mass, as in the genus Lycoris. But in the well- 

 known pigment spots of the star-fish, situated in the interambulacral 

 furrows, at some little distance from the extreme end of the rays, there 

 is received a filament from the ambulacral nervous trunks, which 

 filament becomes dilated into a ganglion on penetrating into the 

 papilla. The papilla is surrounded by spiniform calcareous processes, 

 which are separated from each other by muscles, so as to expose the 

 visual organ to the rays of light ; but when the processes are approxi- 

 mated over the oculiferous papilla, the eye is, so to speak, shut, either 

 for the suspension of vision, or for the protection of the organ. With 

 high powers of the microscope the papilla is seen to be hollowed into 

 numerous little cavities, lined by pigment, and connected at the 

 bottom with the nervous ganglion. These depressions are filled with 

 a very transparent gelatinous matter, forming a slight projection at 

 the surface of the tubercle, and terminated by a convex portion, like 

 the cornea of the higher animals. The presence of this refractive 

 substance gives the eye some claim to be considered as eidoscopic in 

 its character ; and it doubtless serves to collect and concentrate the 

 luminous rays upon the impressionable pigment, and consequently to 

 render the perception of light, and of its different degrees, more 

 intense and perfect. 



Dr. Cobbold, well known for his study of the Entozoa, has published 

 a pamphlet (on a new Entozootic malady) in which, he foretells the 

 almost inevitable increase of parasitic diseases in general, if the pro- 

 posed extensive utilization of sewage be carried out. Eeferring to the 



