352 SUMMABY or CURRENT RESEARCHES RELATING TO 



Actinife are gradually heated from 26-27° to 35-36° C, the movements 

 of alga-bearing or alga-free ActiniEe become more lively, and this is 

 true whether the change is due to sunlight or to artificial heating, 

 with careful exclusion of the light. If alga-bearing Anthozoa are 

 subjected to direct light they are killed, and this not because of the 

 great production of oxygen or the influence of the light, but in con- 

 sequence of the heating ; the production of oxygen does not seem in 

 any way to aftect the result. 



All alga bearing Actiniaj throw off a number of yellow-cells when 

 subjected to heat ; treatment at 30^ for some time or at 35^ for a 

 shorter resulting in the presence in the surrounding water of irregular 

 brown masses, which contain a large number of yellow-cells, which 

 were still completely cai:)able of development or of assimilation ; and 

 this even obtained when the Actiniae were themselves killed. 



Yellowish-green and yellow Zooxanthellce are only found in 

 animals living on the surface of the sea (Radiolaria, Globigerinae, 

 Siphonoj^hora, Ehizostomidae) ; brown cells in those which live at a 

 slight dej)th, and red algae in sponges, which live somewhat deeper 

 (15-35 m.). 



Division of Lower Invertebrates.* — C. Biilow gives in a collected 

 form some of the scattered information and theories which aftect the 

 question of the apparently voluntary division, with subsequent re- 

 generation, of Ccelenterates, Echinoderms, and Worms, and gives 

 some unpublished observations as to regeneration in the Gephyrea. 



Examining some living specimens of Phascolosoma vulgare and 

 Aspidosiphon muelleri, he removed from five of the former and three 

 of the latter a portion of their proboscis ; the oesophageal ring was 

 separated from the rest of the body, as well as the tentacles, the 

 mouth, part of the retractor muscles, &c. In from three to five weeks 

 all the lost parts were replaced, and the only apparent difference was 

 to be found in a brighter colour and a greater transparency. 



MoUusca. 



Chromatophores of Cephalopoda-f— E. Blanchard finds that the 

 chromatophore of the Cephalopod does not differ in the general 

 characters of its structure from that of Fishes, Batrachia, or Lizards 

 {ChamcBleo) ; it is a simple connective-cell charged with pigment, and 

 possessing to a high degree the power of protruding amoeboid pro- 

 cesses from the centre of its amorphous central mass. All the activity 

 is seated in the chromatophore itself, and the sui-rounding tissues take 

 no part in accomplishing its movements ; in fact, it may be well com- 

 pared to an amceba, charged with pigment, and independent of the 

 dermis which incloses it. 



This amceba, however, is under the influence of the nervous 

 system, as the observations and experiments of Briicke, Bert, and 

 others have already demonstrated ; but it is not possible to agree with 

 Harting in thinking that the radiating fibres seen in Cephalopods are 



* Biol. Centralbl., iii. (1883) pp. li-20. 

 t Comptes Rendus, xcvi. (1883) pp. 655-8. 



