8 
POPULAR SCIENCE REVIEW. 
both instances a distinct separation of the organism into cortical 
and medullary portions took place. Lieberkuhn also notices in his 
swarm-spores an abundance of what he terms ‘‘germ-granules.”' 
These are cells, sometimes diameter, which, in 
addition to the ordinary granular matter, contain more distinct 
granules, regarded by Lieberkuhn as reproductive. Carter’s 
ovi-bearing cells are probably identical with the above. Though 
it is not always easy to identify the objects described by indivi- 
dual writers, there is no doubt that the medullary substance, both 
of the developing gemmules of the swarm-spores and of the 
matured sponge, abound in cells (tig. 13) or sarcoids filled with de- 
finite granules, which latter, in their turn, frequently develop into 
sarcoids. These reproductive sarcoids are sometimes scattered 
through all parts of the Spougilla, at others aggregated into 
groups. Carter found what he regarded as “ zoosperms,” and 
Lieberkuhn believed that he had discovered “ spermatozoa ” in 
Spongilla ; but I cannot regard the existence of these fertilising 
cells as proved in either of these instances. The possibility of 
feeding the Spongilla is a much better established fact. Carter in- 
troduced carmine into the water, and, after a while, discovered that 
particles of the colouring matter had been carried, through the 
apertures of the investing membrane, into the canals, whence 
they had reached and become imbedded in the substance of the 
sarcoids, as would have occurred amongst true Amoebae under 
similar conditions. 
Fig. 
1 . 
2 . 
V 
3. 
4. 
5. 
6 . 
7. 
8 . 
9. 
V 
V 
10 . 
11 . 
V 
12 . 
DESCRIPTION OF THE PLATE. 
Young Spongilla investing a small branch. 
Fragment of Spongilla dried up : a, network of spiculs aggluti- 
nated by desiccated sarcode ; 5, reproductive gemmules. 
Rod of skeleton composed of aggregated smooth spicules. 
Single smooth spicule of No. 3. 
Small detached mass of sarcode (after Carter). 
Separate “ cells ” or sarcoids : un ciliated ; c-c?, mono-ciliated 
(after Carter). 
Separate siliceous gemmule : a, hilum. 
Fragment of the exterior of the gemmule with the amphidiscs in 
position, as seen by transmitted light. 
Vertical section of tig. 8 : «, outer layer of stellate discs ,• 6, inner 
layer. 
Detached amphidisc. 
Portion of the surface of the membrane investing the medullary 
mass of the gemmule (after Carter). 
Diagram of section of a gemmule : coriaceous investing mem- 
brane ; 5, medullary mass of “ cells j ” c, layer of amphidiscs ; 
hilum. 
