312 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
hypostome and a portion of tlie body. Fragments from isolated buds 
form new polyps more rapidly than do larger pieces from a full-grown 
animal. 
Classification of Siphonophora.* * * § — Dr. K. C. Schneider concludes a 
long paper on the Siphonopliora, which is mainly of systematic interest. 
He defines the order as follows : — Free-swimming colonies of hydro- 
polyps, with regularly arranged components, both medusoid (swimming- 
bells, pneumatophore, and gonophores) and polypoid (covering pieces, 
adhesive threads, and polyps). There are four suborders : — (1) Caly- 
cophorm, without pneumatophore, including Prayidae and Diphyidm; 
(2) Physophorae, with pneumatophore and swimming-bells, including 
Apolemidse, Agalmidm, &c. ; (3) Cystonectoe, with unchambered pneu- 
matophore and no swimming-bells, including Physalia, BMzophysa , &c. ; 
(4) Chondrophorae, with chambered pneumatophore and no swimming- 
bells or main stem, Velella and Porpita. 
Regenerative Phenomena in Tubularia.f— Herr Hans Driesch 
finds that a “ reparatory zone,” marked by a red substance, appears at 
a certain distance from the wound-surface, and forms a new Anlage, 
from which reparation proceeds. Decapitated polyps partially split longi- 
tudinally may form two complete hydranths. The reparation is quicker 
the second time. Oral reparation retards simultaneous aboral reparation. 
There is no proximal regeneration, i. e. tentacles do not regenerate 
hydranth, nor liydranth ccenosarc. 
Driesch distinguishes somewhat subtly between different modes of 
regeneration, for which it is difficult to find English equivalents. A 
general result of interest is the absence of abnormalities; even when 
the usual reparatory process is disturbed the final result is normal. 
Hew Hydroids.J — Kristine Bonnevie discusses the classification of 
Hy droids, and describes numerous new forms collected by the Norwegian 
North Sea Expedition : — four new species of Tubular ia, a new genus 
Lampra with three species, a new genus Gymnogonos, two new species 
of Eudendrium, four of Hy dr actinia, four of Myriothela , and two of 
Coryne. 
Porifera. 
Spicules of Clathrinid8e.§ — Mr. E. A. Minchin, in the first instal- 
ment of “Materials for a Monograph of the Ascons,” deals with the 
origin and growth of the triradiate and quadriradiate spicules in the 
family Clathrinidee. In an introductory account of the structure of 
Clathrina, he recognises, apart from the sex-cells, two constituent layers 
in the sponge body, besides a class of cell-elements which seem, pro- 
perly speaking, to belong to neither layer. Thus he describes : — 
(1) The gastral layer, consisting of the collar-cells lining the 
interior. 
(2) The dermal layer, consisting of («) the external neuro-muscular 
* Zool. Anzeig., xxi. (1898) pp. 185-200. 
f Arcli. Entwickmecli., v. (1897) pp. 389-418 (14 figs.). See Zool. Centralbl., 
v. (1898) pp. 10-12. 
X Zeitschr. wiss. Zool., lxiii. (1898) pp. 465-95 (3 pis. and 1 fig.). 
§ Quart. Journ. Micr. Sci., xl. (1898) pp. 469 587 (5 pis. and 3 figs.), 
