328 PROFESSOR ALLMAN. 



internal thin granular layer of protoplasm which lines the 

 structureless membrane throughout its whole extent, and 

 which receives the extremities of the radiating processes from 

 the central mass. Under the action of iodine solution and of 

 other reagents the protoplasm layer may be seen to detach 

 itself from the outer structureless membrane, and along with 

 the radiating bauds contract towards the centre (fig. 4). It 

 admits of an obvious comparison with the primordial utricle 

 of the vegetable cell. 



The flagellum which is given off close to the margin of the 

 mouth is a flattened band-like organ gradually narrowing 

 towards its free extremity. Its axis presents throughout its 

 whole length close transverse striae. It seems to have the 

 power of elevating its edges so as to render one of its surfaces 

 concave, and thus becomes converted into a semi-tube which 

 may assist in the conveyance of nutriment towards the mouth. 



The nucleus is a spherical vesicle with clear colourless 

 contents, among which minute transparent oval corpuscles 

 may usually be detected (fig. 5, ci). When acted on by acetic 

 acid the difference between the contents and the wall becomes 

 very apparent, and the contents may now be seen con- 

 tracted towards the centre as a minutely granular mass with 

 some of the oval corpuscles entangled in it {h). 



The radiating offsets which extend from the central proto- 

 plasm to the peripheral layer contain well-defined clear re- 

 fringent corpuscles (fig. 6), which may sometimes be seen to 

 slowly change their relative places as if under the influence of 

 feeble cyclotic currents. Though these movements are far less 

 marked than the very distinct cyclosis of the vegetable proto- 

 plasm, Ave cannot overlook the close resemblance between the 

 radiating offsets in Noctiluca and the protoplasm filaments 

 which extend from the nucleus to the primordial utricle in 

 the vegetable cell. I have never seen anything in the radi- 

 ating protoplasm filaments of Noctiluca which can be com- 

 pared with the projection and retraction of the pseudopodia 

 in a Rhizopod. The peripheral layer contains scattered 

 through it numerous minute cell-like bodies. These are 

 spherical and of various sizes ; in the larger a distinct central 

 nucleus may be detected (fig. 7). 



It is scarcely correct to regard the central mass of proto- 

 plasm as a true stomach ; I have failed in finding any evidence 

 of a permanent gastric cavity, and I regard the protoplasm 

 mass to which the gullet leads as representing the protoplasm 

 of the Infusoria, and, like this, allowing of the solid food being 

 forced down into it from the gullet and encysted there in 

 extemporaneously formed vacuolee. The food also frequently 



