596 SUMMARY OF CURRENT RESEARCHES RELATING TO 



sotirch for unicellular algfc, moreover, yielded negative results. The 

 fact that in sponges lipochromes so often accompany cbloropliyll, and 

 sometimes replace it, would go to show that the step from a lii)ochrome 

 to a chlorophyll is not a great one ; and it is highly probable that these 

 pi foments are concerned in the formation of fatty matters, perhaps from 

 the waste carbonic anhydride given off during the katiibolic changes in 

 the tissues, and from the water in which they arc bathed ; carbohydrates 

 are perhaps similarly formed. I'his would coincide with the views of 

 Schunck, who regards chlorophyll as a respiratory pigment, but probably 

 a carbonic acid-carrier, not an oxygen-carrier. In sponges, the histoha^- 

 matin, when in-cscnt, has probably the function of an oxygen-carrier. 

 A chart of spectra, with measurements, accompanies the paper. 



Gemmules of Silicispongige.* — M. E. Topsent describes the occur- 

 rence of gemmules in Chalina ociilafa, C. gmcilenta, Cliona vastijico, 

 Suheritcs ficus. They consist of large cellular elements with aggregations 

 of bright granules, and of an envcloi^e of keratode, but they exhibit no 

 foramen nor special spicules. Those of the first-named species occur on 

 the lower part of the firm stalk, and arc somewhat complex. Bowerbank 

 seems to have described a Chalina with gemmules as a new species, 

 Diploflcmia vesicula. In Chalina gracilenta they occur close upon the 

 substratum ; in Cliona, close beside the perforated substance ; in Suherites 

 clomuncula and S. Jicns they have a similar position near the shell or 

 substratum on which the sponge is seated. Carter saw them, and re- 

 garded them as arrested ova. Except in Cliona vastijica the gemmules 

 become mature in spring ; in this species they occur all the year round, 

 and contemporaneously with the sexual reproduction. 



Silicoblasts.t — Herr Noll describes the silicoblasts of some siliceous 

 sponges. In Dcsmacidon hosci N. he found on the strands of skeletal 

 si)icules traces of very large spindle-shaped cells,' which seemed to be 

 either spongioblasts or silicoblasts. Similar cells were seen in Sponjilla 

 fragilis. They inclosed in some cases minute incijiicnt spicules. A 

 cell seems to become elongated, its content becomes thin and clear, the 

 central filament appears as a darker streak quite inclosed by the cell. 

 A\ ith the growth of the spicule the protoj^lasm disajipears, leaving in 

 some cases a very thin envelope. In some cases the cells which form 

 the spicules contain tsvo nuclei. 



Survival of Spongillse after Development of Swarm-larvse.i — Ilerr 

 M. Weltner has examined the common belief that reproduction causes 

 the death of Spongilla. After various failures in the attempt to keep 

 alive for a long time examples of Eplujdatia fluviatilis, he found it easy 

 of accomplishment with young Si:)ongilla! reared from larvae. A de- 

 cidedly female Spongilla was kept alive for nearly four months after the 

 issue of the last larva. In opposition to the statements of Lieberkiihn 

 and Mctschnikoff, it was found that dermis, excurrcnt tubes, and 

 flagellate chambers and canals do not completely disappear in the 

 perennial sponges of the Tegelsee. The author agrees with Gutte 

 that in E. fluiiatilis there can be no question of a decided seasonal 

 difierence, or of a true alternation of generation, such as, according to 

 Marshall, occurs in Spongilla lacustris. 



* Comptes Rendu3, cv. (1888) pp. 1208-1300. 



t liiol. Ceiilralbl., vii. (18S&) pp. 767-8 (GO Versamnil. Dcutsdi. Natuif. \\'ies- 

 badcn, 1887). J Ann. and Mag. Nat. Hist., i. (1888) pp. 840-3. 



