280 RECORD OF CURRENT RESEARCHES RELATING TO 



observed in liis tank at Trieste. These embryos i>roved to belong to 

 Halisarca lohularis, and to have been formed as buds, protruded and 

 constricted off from encrusting masses which grew in the tank. 

 They consist of spheres of 2 to 3 mm. in diameter ; their surface 

 is set with finger-like processes, which are solid and are parts of the 

 gelatinous body-wall. 



These processes contain a number of sac-shaped chambers, some 

 scattered, some aggregated, which open by a distinctly defined mouth 

 into the central cavity of the bud, and by from two to four narrow canals 

 or pores, to the exterior. The cavity of the bud is filled by a clear 

 liquid. The parietal sacs are lined by collar cells up to the mouth ; 

 the canals which ojien from the exterior, by flat polygonal cells agree- 

 ing with those of the body-cavity ; the external surface of the bud is 

 covered by a uni serial layer of similar, but more granular, nucleated, 

 non-ciliated, epithelial cells ; those, however, at the ends of the above- 

 mentioned finger-like organs, are provided with protoplasmic pro- 

 cesses endowed with amceboid movements. Between these two layers 

 lies a connective tissue exactly similar in character to the gelatinous 

 layer of Halisarca and other sponges, containing large numbers of 

 branched cells, sometimes anastomosing. No skeleton is to be seen. 



The buds originate by the outward swelling of the normal papillae 

 of the sponge; they take the form of inflated masses, and become 

 detached by the constriction of their bases. The process begins in 

 the middle of the sponge-crust and proceeds to the edges ; the whole 

 of a small crust carrying several papillae has been observed thus to 

 swell out and become detached as a large bud. After a chiefly free- 

 swimming existence of about fourteen days, the buds sink to the 

 bottom, spread out and become attached by their base, and assume the 

 form of young Halisarcce. 



Any doubts as to the occurrence of these phenomena in the normal 

 and healthy state are set at rest by the observation of the i)rocess in 

 all its details in sj)onges freshly brought from the sea, showing that 

 buds from such specimens of H. lohularis var. ccerulea, after an indepen- 

 dent life, settle down and reproduce as flattened, blue masses, the 

 original sponge with all its varietal peculiarities. 



It is noteworthy that the appearance of this mode of reproduction 

 occurring in autumn, after the termination of the sexual process, 

 must be very important for the preservation and diffusion of the 

 species. 



Muscle-fibres of Sponges.* — Mr. W. J. Sollas, in describing some 

 new sponges dredged by the Eev. A. M. Norman on the Norwegian 

 coast, says that in Stelletta Normani the fibres are the best marked he has 

 yet met with in any sponge, and they likewise most closely resemble 

 the organic muscle-fibres of the higher animals. They are about • 0066 

 inch long and 0-0003 broad, fusiform, hyaline, colourless, and of 

 sharply marked contour ; their nucleus or axial thread, as it may be 

 more correctly termed, is fusiform, homogeneous, faintly bluish in 

 colour, highly refringent, and • 0035 inch long. With polarized light 



* ' Anu. and Mag. Nat. Hist.,' v. (1880) p. 137. 



