314 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Attention is directed to the peculiar parenchyma. It is ahnost entirely 

 composed of something like lymphoid connective-tissue. It consists of 

 flat cells with delicate membranous processes, forming a sort of syncytium. 

 There seems to be a close relationship between Spirastrella and the 

 boring sponge Cliona, but the former only fills up holes without any 

 boring. 



Regeneration in Sponges.* — K. Miiller has experimented with 

 Spongilla lacustris and Ephydatia milUeri, which can regenerate from 

 pounded-up material pressed through a linen cloth. The material in- 

 cludes amoebocytes, thesocytes, scleroblasts, and modified collar-cells. 

 Aggregates are formed, like gemmules, with flat epithelium (pinacocytes) 

 externally. If there is a syncytial stage it is of very short duration. 

 The flagellate chambers arise from large multinucleate cells ; the nuclei 

 move to near the periphery ; each gathers a plasmic portion around 

 it ; each of these units forms a flagellum ; the internal residue breaks 

 down. Mitosis was observed both in amoebocytes and thesocytes. 



Fresh-water Sponges of Clare Island.f — Jane Stephens reports the 

 occurrence of five species on Clare Island and the adjacent part of the 

 mainland — Simngilla lacustris, S. frai/iUs (new to Ireland), Ephydatia 

 ffuviatilis, E. miiUeri, and Heteromeyenia ryderi. The last species occurs 

 in various forms, differing in appearance and in spicules. Many of the 

 slight varieties of spicules are figured. It is probable that the differences 

 are due to environmental influence. 



Protozoa. 



Studies on Amoebse.! — A. Alexeieff discusses the amoebse of the 

 Umax group, which have a cosmopolitan distribution, and are strictly 

 saprozoic, not parasitic. In distinguishing different kinds attention 

 must be paid to the structure of the nucleus in its vegetative state, to 

 the mitosis, and the fine structure of the wall of the cyst. He defines 

 Nsegleria g. n., which has a bi-flagellate stage, and Hartmannia g. n. 

 The latter does not show in its division the large polar bodies charac- 

 teristic of the former. For the amoebge parasitic in Vertebrates a new 

 genus, Frodamreba, is erected. Minchin's Malpighiella is quite distinct 

 from Proctammba, on the one hand, and Entamceba of the cockroach, on 

 the other. 



Flagella Stage in Life-history of an Amoeba. § — A. Alexeieff has 

 observed flagellate spores in the liie-historj of A77ueba punctata Dangeard. 

 The two flagella are formed from nuclear material — the plastin material 

 especially. They may be followed to the nucleus, but they are usually 

 inserted on two small basal granules. A fibril or rhizoplast may be seen 

 running from the basal granules to the nucleus. lu^. Umax Duj. there 

 is also a flagellate stage. 



* Arch. Entwickl., xxxii. (1911) pp. 397-446 (28 figs.). 



t Proc. Irish Acad., xxxi. (1912) Clare Island Survey, pt. 60, pp. 1-18 (1 pi.). 



t BuU. Soc. Zcol. France, xxxvii. (1912) pp. 55-74 (5 figs.). 



§ C.R. Soc. Biol., Ixxii. (1912) pp. 126-8. 



