40 SPONGID.E. 



similar to the spermatozoa of Tethya have been 

 recently detected by Lieberkiihn. 



6. Carter has described certain '* seed-like 

 bodies " {fig. 8, a) which are found embedded ia 

 the gelatinous substance of Spongilla. Each of 

 these consists of a round or ovoid coriaceous cap- 

 sule, the sm'face of which when magnified, pre- 

 sents a hexagonally tessellated appearance (/), and 

 is surrounded by a zone of the peculiar asteroid 

 spicula (b, c) to which we have already referred 

 (p. 36), these being embedded in a coating of gela- 

 tinous matter. Within the capsule are numerous, 

 transparent, spherical "ovi-bearing cells" con- 

 taining granules and germs in their interior {d, e), 

 and surrounded by a cortical layer of peculiar 

 nucleated cells. MTien arrived at matmity the 

 contents of the seed-like body escape through the 

 hilum or aperture with which it is provided, 

 " under the form of a gelatinous mass, in which 

 the ovi-bearing cells and their contents appear to 

 be embedded entire." Next, spicula are developed 

 and with them a delicate pellicle or "investing 

 membrane " which would seem to be formed from 

 the nucleated cells of the cortical layer. This 

 becomes separated by an interval or " cavity "" 

 from the " parenchyma " or gelatinous substance 

 enclosing the ovi-bearing cells. Apertures sub- 

 sequently originate in the investing membrane, 

 whilst at the same time a canal system is being 

 formed in the parenchyma ; and, finally, the ovi- 

 bearing cells are developed into a number of 

 stomachal or " ampullaceous " sacs, which open 

 into the incm-rent canals. 



From the investigations of Lieberkiihn it would 

 appear that the propagation of Spongilla is some- 



