166 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
and “ pupil ” arrangement. Nor did they meet with any elements which 
could possibly be considered as intermediate stages between normal 
choanocytes and normal parenchyma cells. The isolation-method of 
studying the cells of sponges is strongly recommended. 
Classification of Monaxonida.* — Prof. E. Topsent argues in favour 
of the following rearrangement. He recognises two sub-orders : — 
I. Halichondrina, including Haploscleridse, Poeciloscleridae, and 
Axinellidae. 
II. Hadromerina. — Section A. Clavulida with monactinal mega- 
scleres, including the families Clionidae, 
Spirastrellidae, Polymastidae, Suberitidae, 
and Mesapidae. 
Section B. Aciculida (with diactinal mega- 
scleres), including the families Coppa- 
tiidae, Streptasteridm,Tethyidae,and Stylo- 
cordylidae. 
Arctic Calcareous Sponges.']' — Dr. L. L. Breitfuss has followed his 
previous studies on Calcarea with a catalogue of those known to occur 
in the Arctic region, which he divides into five sub-regions. The list 
includes 42 species. 
Protozoa. 
Reproduction of Ciliata.:]: — Herr D. Joukowsky has repeated Maupas’ 
famous experiments, and we see the need of caution in the somewhat 
different results reached by the two observers. 
In Pleurotricha lanceolata over 458 generations were observed with- 
out the occurrence of degeneration. The size of the individuals depends 
mainly on the nutrition ; the rate of multiplication varies markedly with 
the temperature ; disturbances are apparently produced by the accumu- 
lation of waste products in the fluid. Degeneration seems, according to 
the author, to be due not to the number of generations merely, but to the 
rapidity of their succession. 
After five months’ culture, Paramsecium caudatum showed no nuclear 
degeneration, but a marked reduction of cilia and a resulting sluggish- 
ness. In P. putrinum effective conjugation between the descendants of 
one individual was observed, but the author admits the probability that 
this has its limits. 
Pseudopodia in a Dinoflageilate.§ — Dr. O. Zacharias observed on 
specimens of Gymnodinium palustre (one of the fresh-water Peridinieae) 
the formation of pseudopodia in a manner very like that in Diplophrys 
Archeri. The fact is suggestive of the relationship, which Klebs has 
maintained, between the Gymnodinieae and the Rhizomastiginae. Schil- 
ling has described the protrusion of pseudopodia in Gymnodinium Jiya- 
linum , which is able to move by this means. This is not the case in 
G. palustre , where the pseudopodia are possibly nutritive, in relation to a 
probable — though unproved — saprophytic phase. 
* Arch. Zool. Exper., vi. (1898) pp. 91-113. 
t Arch. Naturgesch, lxiv. (1898) pp. 277-316. 
X Yerh. Nat. Med. Ver. Heidelberg, vi. (1898) pp. 17-42. See Zool. Centralbl., vi. 
(1899) pp. 42-3. § Biol. Centralbl., xix. (1899) pp. 141-4 (9 figs.). 
