8 Spong. 
XVII. SPONGLE. 
together in a group connecting a cortical cavity with a canal of the interior. 
The subcortical chones of Vioa and Papillella consist of an inner zone of 
massive cells and an outer ring of circular spindle-cells. Outside the 
latter radial spindle-cells are observed traversing the longitudinal spicule 
bundles which usually surround the chones. Transverse membranes 
traverse the main canals of Vioa and Papillella at frequent intervals. These 
membranes are thickened towards the centre and perforated in the middle. 
They are (in Vioa) covered with numerous scattered microsclores and 
composed of an inner zone of massive, often radially elongated, more or 
less cylindrical cells, a middle zone of circular spindle-cells and outer zone 
of radial spindle-cells, occupying the distal, thin portion. In consequence 
of their similarity to the chones Lendenfeld has named these structures 
“chonal membranes.” Doubtlessly the radial and the circular spindle- 
cells of all these chones and chonal membranes are to be considered as 
contractile elements, the former as dilatatores and the latter as constric- 
tores of the chonal canal. 
f. Cortex [cf. Titles 20, 21]. 
In most Clavulina Lendenfeld (21) finds a cortical layer destitute of 
ciliated chambers. In Tethya , in some species of Suberites , in Placospongia , 
etc. this layer is dense and fibrillar. In Suberanthus, A stromimus, etc. 
the cortex is so rich in lacunose cavities, that it appears more or less 
foam-like. The fistulose appendages of Polymastia are composed of an 
inner lacunose, foam-like tissue and an outer dense fibrillar rind. The 
limit between cortex and pulpa is usually very well defined. Spindle-cells, 
probably of contractile nature, are often met with in the cortex, chiefly 
around the cortical canals. Sometimes radial dilatatores and circular 
constrictores can be distinguished. The soft tissue between the armour- 
plates of Placospongia consists chiefly of transverse fibres. In the cortex 
of Suberites aaptus two layers of nodulose masses of some organic, probably 
reserve-nourishing material are met with. Heaps of rounded granular 
cells, which may be young buds, are observed in the cortex of Tethya. In 
the cortex cells occur containing the pigment granules which give to the 
sponges their colour. Different Clavulina show a great diversity in the 
structure of their cortex (Lendenfeld, 20, 21). 
o. Puli* a [cf. Titles 20, 21]. 
Lendenfeld (21) finds the larger canals in many Clavulina surrounded 
by tissue similar to that of the cortex. Usually circular spindle-cells form 
the innermost layer of the canal wall. Sometimes also longitudinal and 
radial spindle-cells occur in the deeper layers. The longitudinal spindle- 
cells are met with chiefly round the canals which traverse the papillae 
of Vioa and Papillella longitudinally. They cause the retraction of the 
papillao. 
Massive granular colls, probably spongoblastic in nature, wore observed 
by Lendenfeld (21) overlying the basal sponginplate in Suberites fug ax. 
In Phyllospongia dendyi Lendenfeld (20) observed long-necked spongo- 
blasts similar to the superficial flask-cells. In the sections each of these 
spongoblasts appeared attached to a small sponginplate, the latest 
addition to the fibre, but these sponginplates were torn from the fibre 
by the action of the reagents employed and separated from it by a little 
space in the sections. 
h. Sexual Cells, Propagation and Development [cf. Titles 3, 21]. 
Breitfuss (3) describes the ripe ovum of Ascandra hermesii as a sphere 
0‘17 mm. in diameter containing a large nucleus with one large and 
