352 M. Reichert on the Morphology and Motory Phenomena 
the cortical substance of the soft body probably also possesses 
the property of producing excretions by which animals forming 
its food are killed. It also exhibits phenomena of sensation ; for 
the extended processes retract on contact with foreign bodies. 
It is probably also a respiratory organ, and the active motion 
of its granules may contribute to the constant change of the sea- 
water. From the manner in which the many-chambered Fora- 
minifera enlarge and grow, it can scarcely be doubted that it 
plays an important part in this formative process. Lastly, I 
have observed that segments separate from it and apparently 
disappear entirely ; so that it must undergo a kind of regenerative 
process, and restoration must take place in the remaining corti- 
cal layer from regeneration by intussusception. 
4. The contractile cortical substance of the body of the Poly- 
thalamia in a state of rest cannot be recognized as a distinct 
constituent, even with the aid of the microscope; it forms so 
thin a layer that its optical section, with the thickness of the 
body of the animal and the apparently shapeless central sub- 
stance of the body containing the vesicles, appears merely as a 
boundary line of the latter and without a double contour. But 
it is distinctly visible when thickened by contraction and evolving 
the processes, as well as when the central mass containing the 
vesicles is passively pushed against it. Although it may origi- 
nally have been formed from a group of cells, yet when fully de- 
veloped there is not the slightest trace of any distinct compo- 
nents. It is perfectly hyaline and colourless in the pseudopodia, 
but sometimes becomes coloured at condensed spots. At these 
condensed spots and in the larger processes it also appears finely 
granular, and hence appears under the microscope as if it con- 
tained larger granules. Although in other low invertebrate 
animals the presence of similar true granules in the contractile 
substance is undoubted, this must at present be denied in the 
case of the contractile substance of the Polythalamia, as the 
granular appearance only occurs during the state of contraction, 
and must therefore be attributed to irregularities of the surface. 
5. In regard to the motory phenomena of the body of the 
Polythalamia, which must be brought into connexion with the 
contractility of the cortical substance, I distinguish active and 
passive. To the passive belong the movements and the often ap- 
parently rotating motions of the central substance of the body, 
arising from the peristaltic constrictions of the contractile mantle 
and the locomotion of the entire body. All the active motory 
phenomena are recognizable by general or local alterations in 
the external form and morphological structure of the contractile 
cortical substance. 
a. The contractile property of the cortical substance is exhi- 
