Miscellaneous. 457 



not to make use of materials hardened in alcohol ; under such con- 

 ditions, in fact, it becomes difficult to distinguish the protoplasm 

 from the nucleus. In certain cases, at any rate, I think I may 

 ascribe the mistakes of some authors to the use of materials 

 hardened in alcohol. Treatment with hypochlorite of soda in very 

 dilute solution has furnished good results. 



To sum up : the autherozoids of the Hepaticfe are formed at the 

 same time by the nucleus and the protoplasm of the mother-cell. 

 The body of the anthcrozoid, therefore, not corresponding solely to 

 the nucleus of the mother-cell, but to the nucleus and protoplasm 

 together, there is not only a change of form of the elements of the 

 cell, but there is at the same time a change of properties and of 

 structure. The body of the anthcrozoid, which is more refractive 

 and more homogeneous than the protoplasm or the nucleus, is also 

 more difficult to stain with reagents, especially at the commence- 

 ment of its formation. A complete transformation of the elements 

 of the cell has taken place ; we may therefore say that in becomhig 

 converted into an antherozoid the mother-cell has undergone a total 

 renovation. — Comities Rendus, March 19, 1888, p. 876. 



On the Gemnndes of some Marine Siliceous Sponges. 

 By M. E. TopsENT. 



As in the Spongillte, multiplication by means of gemmules is 

 observed in adddition to sexual reproduction in many siliceous 

 sponges common on the shores of the Channel and belonging to 

 different families, such as Chalina ocidata, C. gracilenta, Cliona 

 vastifica, and Suherites Jicus. 



The asexual germs which originate in the deeper parts of these 

 various sponges consist essentially (1) of rather large elements, 

 darkened by a great accumulation in their protoplasm of large shining 

 granules, which conceal the cell-nucleus ; and (2) of a keratode 

 envelope. In none of the marine species here in question do the 

 gemmules attain the same degree of complication as those of the 

 Spongillce ; their envelope is not pierced by a foramen, and the 

 spicules with which it is often armed are not special ones. 



The gemmules of Clicdina ocidata are, however, still rather com- 

 plex. They are developed in small numbers (not more than thirty) 

 in the lower region of the hard and apparently lifeless peduncle of 

 this branching sponge. Attached to the yellowish fibres of the 

 skeleton they appear as ovoid bodies of a milk-white colour, three 

 or four times the size of the gemmi;les of Spongilla Jiuviatilis for 

 example. Their keratodic envelope is supported throughout its 

 whole extent by acerate spicules arranged parallel to each other ; 

 further, some horny fibrils, also containing spicules, intercross iu 

 the middle of the internal cellular mass. 



Bowerbank, without knowing it, had discovered these gemmules 

 in a very short piece of peduncle which he took for a new sponge 

 (Shetland Islands) and named Diplodemia vesicula. From the 

 description of this species and its ovaries, 0. Schmidt in 1870 

 thought he recognized a fragment or a young form of a Chalinean, 

 Now it seems no longer doubtful that the unique Diplodemia is the 

 broken foot of a Chalina ocidata. 



