STRUCTURE OF HALIPHYSEMA TUMANOWICZII. 481 



in such a way as to crack the test and roll away its frag- 

 ments from the soft kernel within. In this Avay I succeeded 

 in obtaining several more or less complete ^' cores " or " ker- 

 nels," such as that figured in PI. XXII, fig. 2. 



These were sufficiently transparent to admit of their exa- 

 mination by the highest powers of the microscope, and by 

 teazing stained specimens it was easy to obtain complete 

 evidence of their structure. 



The " core " of Haliphtjsema — I speak of the Jersey 

 specimens, not of Professor Haeckel's — is a continuous mass 

 of protoplasm, exhibiting no central cavity, and devoid of 

 " cell-structure." On its surface this core is fluted and 

 moulded to the shape of the adjoining spicule-fragments 

 which form the test (see PL XXII, figs. 2 and 11 r). There 

 appears to be no differentiation of a "cortical substance'^ on 

 the surface of the core, though the protoplasm is more free 

 from granules here than it is deeply. 



The nuclei. — Scattered in the protoplasm are an immense 

 number of vesicular bodies averaging -j-j__th inch in dia- 

 meter and of very constant size. These vesicular bodies 

 stain deeply ; their walls are thick and their contents finely 

 granular or else hyaline. The wall of the vesicles stains 

 much more deeply than their contents. In the living stale 

 these vesicular bodies are spherical in form ; after the action 

 of chromic acid or of alcohol they exhibit various conditions 

 of collapse and shrinking; some of these are drawn in fig. 

 10. In teazed chromic-acid specimens the vesicles are 

 readily isolated, frequently leaving a " bed " or space in the 

 protoplasm from which they have been disinterred. 



The term " vesicular nuclei " may be applied to these 

 bodies which certainly constitute the most obvious structural 

 feature of the soft substance of Haliphysema. 



We have not to go far to find their parallel amongst the 

 Protozoa. Though they differ in the fact that they are 

 very abundant, and in their sharp emargination, from the 

 nuclei recently discovered in Foraininifera by F. E. Schulze 

 and Hertwig, yet it seems most probable that they are only 

 an elaborated condition of such nuclei. In abundance and 

 sharpness of outline they are paralleled or even surpassed by 

 the vesicular nuclei of Pelomyxa, and it is also a conclusion 

 admitting of little doubt that the peculiar oat-shaped cor- 

 puscles of Labyrinthula and Chlamydomyxa are further 

 examples of the existence of very numerous sharply-defined 

 nuclei existing in an organism which is, nevertheless, uni- 

 cellular. 



The vesicular nuclei which are now figured as character- 



VOL. XIX. NEW SER. I I 



