INFUSORIA. 74 



mity of which issues a peculiar curved stalk or ap- 

 pendage, marked by transverse lines, which would 

 seem to be made use of as an organ of locomotion. 

 Kear the base of this * tentacle ' is placed the 

 mouth, provided on one side with a tooth-like pro- 

 jection. The mouth leads into an 'oesophagus,' 

 from the bottom of which a delicate flickering 

 filament or ' cilium ' is sometimes protruded. 

 The oesophagus passes into a dilatable digestive 

 cavity which is supposed by Mr. Huxley to be con- 

 nected with a small funnel-shaped depression or 

 * anal aperture ' situated in the midst of a flattened 

 space behind the mouth. An oval 'nucleus,' 

 rather less than '002 of an inch in length, lies in 

 front of the digestive cavity. The body of Kocti- 

 luca is invested by a rather firm membrane, 

 destitute of cilia, beneath which occurs a gelatinous 

 layer richly furnished with minute granules. From 

 this layer arises a network of delicate granular 

 ' fibrils,' which unite to form coarser fibres as they 

 proceed towards the centre of the body, until finally 

 they reach the nucleus and digestive cavity. The 

 diameter of Noctiluca varies from '04 to '01 of 

 an inch. It is, perhaps, the most frequent som-ce 

 of the diffused luminosity of the sea in tempe- 

 rate climes, the light which it emits being, as it 

 were, the combined result of a rapid succession of 

 vivid scintillations. 



Noctiluca multiplies by spontaneous fission. 

 Within the body of this animal Busch observed the 

 existence of certain brown masses, containino- ora- 

 nules m their interior. It is not certain whether 

 these were true ova or merely the result of a 

 process of gemmation. In other Noctilucce the 

 same observer detected peculiar germ-like bodies, 



