BIOLOGY. 
Spcm g. 17 
reticular membrane, made up of peculiar choanocytes with flattened and 
ramified bodies which are in organic fusion by means of their lateral 
protoplasmic processes to form a fenestrated syncytial membrane. The 
minute meshes of the network thus formed are freely open, not closed by 
any basal membrane, pace Schulze, and represent so many prosopyles. 
The trabeculae of the dermal layer attach themselves directly to the 
reticular membrane on its outer side. The collars of the choanocytes, 
approximately cylindrical in form, and 5—6/x in length, are free and separate 
from one another. The flagellum is 17-19 /j, in length. The collum and 
basal plate of Schulze could not be found, nor yet the alleged connections 
between the distal portions of the choanocytes ; pp. 128-147.— Chambers 
of Regadrella okinoseana, p. 248 ; Ijima (29). —Flagellated chambers of 
Halisarca dujardini var. rnagellanica\ Topsent (60) p. 44. 
Archseocytes of Euplectellai marshalli and other Hexactinellids, their 
structure and occurrence; groups of them occur in the narrow incurrent 
interspaces between the chambers, and in the deeper parts of the choano- 
some these “archseocyte-congeries” attain a very considerable size, pp. 165- 
172. The archaeocytes give rise to (1) Thesocytes containing numerous 
fat-like spherules, probably reserve nutriment, pp. 173-178 ; (2) repro¬ 
ductive elements, pp. 179-185. The archeeocyte-congeries also appear to 
give rise to reproductive bodies, possibly to larvae, of an asexual nature 
(pp. 185-190).—Archseocytes and thesocytes of Regadrella ohinoseana , 
pp. 247 & 248; Ijima (29).—“Cellules spheruleuses” [archseocytes?] of 
Eurete alicei-. Topsent (58) p. 463.—Archseocytes of Tethya , and their 
role in the budding ; Maas (38). 
(vi) The Germ-Layer Question. 
Sponges composed of a gastral (endoderm) and a dermal (meso-ectoderm) 
cell-layer ; Iaukenthal (34) p. 32.—The observations of Ijima upon the 
structure of the dermal layer in Hexactinellids lead to conclusions directly 
antagonistic to the n i esoderm-theory, still maintained for sponges by 
many authorities ; Minchin in review of Ijima (29). 
C. Physiology. 
(i) General Accounts. —The Physiology of the Bath-Sponge; 
Seurat (52) p. 260. 
(ii) Nutrition.— See Seurat (52). 
(iii) Respiration. —Vacant. 
(iv) Secretion and Excretion.—Pigments, Ferments, etc. — 
Diastases of Suberites clomuncula, with some observations upon those of 
Cydonium gigas and Tethya lyncurium ; Cotte (13). 
(v) Irritability, Contractility, etc. —Contractility in the trabe¬ 
culae of Euplectella marshalli ; Ijima (29) pp. 148-150. 
(vi) Individuality.— Euplectella “rather polyzoic than monozoic”; 
the sieve-plate and its apertures regarded as “a close aggregation of. 
oscula”; the parietal gaps regarded as “secondarily formed oscules”; 
Ijima (29) pp. 37-39 and p. 215. [Cf. n, e, ii, c infra.] 
(vii) Miscellanea. — Experimental Physiology. —Nothing. 
F 2 
1901. [Vol. xxxviii.] 
