384 GEITEEAL HISTORY OF THE INFFSORIA. 



ating filaments " {Huxley^ s Lectures, Medical Times, 1856, vol. xxxiii. p. 511). 

 These granular filaments radiate, from a central portion which seems to 

 serve as a bond of union and a basis of support for all the organs about the 

 oral cavity, to the integument in every direction ; and probably the apparent 

 reticulation of the external membrane is due to the crossing of the very 

 fine terminations of those filaments as they proceed to attach themselves to 

 it. Lying amid the meshes of this fibrous network, chiefly towards the 

 centre of the Noctiluca, are more or fewer vacuolar bodies. " The whole 

 internal network of fibrous tissue," writes Dr. Webb (op. cit. p. 104), " with 

 the manner in which it invests the so-caUed vacuoles, is most beautifully 

 demonstrated by the effect of iodine. The creature dies suddenly, without 

 collapsing. The progress of the fluid can be traced along the fibres into the 

 minutest meshes ; and there remains for a long time a transparent baU, 

 traversed in every direction by the brown fibres, headed with the vacuoles 

 and granules, and having every reticulation on the surface sharply defined." 



The '' vacuoles " referred to are not homologous with those of Protozoa, 

 and, to avoid confusion, another name should be found for them. They are 

 actual sacs or cells, with a definite membranous wall, and thus appear to 

 resemble in structure the contractile sacs of Protozoa. Dr. Webb asserts 

 them to be alimentary sacs ; and we gather from him the following account 

 of them {op. cit. p. 105) : — " When empty, they are usually contracted and 

 grouped near the membranous tube which leads from the oral aperture — 

 a few only being scattered among the internal reticulations. Their situa- 

 tion is constantly changing, sometimes with a steady advance, at others by 

 jerks, while the fibrous meshes with which they are connected undergo a 

 relative alteration in shape. Gentle pressure will occasionally expel them 

 through the oral or anal aperture ; but I have seen them spontaneously 

 ejected mthout ruptm^e, and float away from the body. In one instance 

 where this occurred, and where the contents consisted of granular matter, 

 fragments of Diatomacece, and particles of sand, the sac remained entire for 

 some time. When it burst, the membrane doubled up, the contents escaped, 

 and the bits of silica were characteristically shown with the polariscope. I 

 have never known these gastric pouches, or alimentary substances to be 

 voided by any other outlet than those connected with the central depression." 



At the bottom of the infimdibulum is a large-sized oval, or ovoid, brownish 

 body, of granular consistence, and strongly refracting light, which is the 

 nucleus. It lies in front of and above the gastric cavity, and. Prof. Huxley 

 states (op. cit. p. 54), assumes the appearance of a hollow vesicle when acted 

 upon by acetic acid. Dr. Webb writes {op. cit. p. 106) — " The nucleus may 

 be demonstrated as a nucleated vesicle, sometimes solitary, more frequently 

 with several similar but smaller nucleated vesicles grouped around it. By 

 careful manipulation it may be removed from the other structures ; and as it 

 floats about, its true form is displayed. Seen in one position, you have a view 

 of a round vesicle with a smaller vesicle attached to it by a sort of hour-glass 

 contraction ; in another, of a round vesicle with a central spot, a nucleated 

 cell. I have found the nucleus enclosed in a second membranous envelope 

 with a granular yelk-like fluid, which could be seen pouring out when the 

 membrane gave way." 



The reproduction of the NoctUucida is as yet not understood. Quatrefages 

 and Krohn, Prof. Huxley informs us {op. cit. p. 54), " consider that a process 

 of fissiparous multiplication takes place, and that both of these observers have 

 found double individuals, though very rarely. According to the latter writer, 

 division of the body is preceded by that of the nucleus. I have not had the 

 good fortune to meet with any of these forms ; and the only indication of a 



