12 BULLETIN OF THE BUREAU OF FISHERIES. 



continued fusion of overlapping lobes. The free surfaces of such masses bear projecting lobes like those 

 of the younger stages, and doubtless the mass continues to increase in size by the growth and fusion of 

 these lobes. 



Color, white, frequently with a green or blue cast. Sponge is firm and brittle and generally dirty. 

 It is much infested with worm tubes and overgrown with hydroids and polyzoa. 



The whole surface is abundantly covered with tubular translucent papilla perforated with numer- 

 ous pores. Papillfe may be simple or slightly branched, often bifurcating. They are contractile and 

 may almost entirely disappear. When dilated they are about 3-5 mm. long and i ram. wide. Oscula 

 1-2 mm. in diameter are scattered over the surface of the incrustation and often develop at or near the 

 ends of lobes. They are sometimes mere apertures in the dermal membrane, but more often are raised 

 up on short collenchymatous tubes. The surface in all stages of growth exhibits numerous ramifying 

 and anastomosing canals which extend just below the dermal membrane. Pores are abundantly scat- 

 tered over the dermal membrane and, as above stated; over the tubular papillae. 



Spicules: (i) Style, smooth and slightly curved, i6o-i8o,« by 5-7/1; (2) tylote, smooth, i6o-i8o,« 

 by 5/1 ; (3) sigmas, 20-36/t long: (4) isochelae, i2-24/(long. Internal skeletal framework a loose irregu- 

 lar reticulum of styles, commonly polyspicular, which may in places develop into spiculo-fibers. 

 Spongin seems to be absent. In wall of larger canals tylotes are found. The peripheral or ectosomal 

 skeleton includes (i) tylotes in radiating loose bands which support the dermal membrane, (2) tylotes 

 which project radially from the dermal membrane singly or in tufts of a few, (3) tylotes strewn hori- 

 zontally in the dermal membrane. 



The microscleres are sigmas and isochelae. The latter are isochelae arcuatae (Levisen, 1893), viz, 

 have at each end a median tooth with two lateral alae, and the axis is strongly curved. In the interior 

 especially sigmas are found, although round the larger canals there are some isochelae. In the dermal 

 membrane both isochelae and sigmas are abundant. 



Wall of the pore papillae contains abundant tj'lotes strewn horizontally, and a few isochelae. 



FORMATION OF PLASMODIA. 



The following experiments show that the dissociated Lissodcndoryx cells can carry 

 on the process of fusion with the consequent formation of plasmodial masses of con- 

 siderable size. In one experiment the masses began to die early. In another experi- 

 ment they gave no signs of dying but remained inactive and did not metamorphose. 

 It is more difficult to get this species-tissue free from dirt than that of Microciona. 

 Again the absence of a homy skeletal framework (which by its elastic recoil would tend 

 to scatter the sponge cells) may make it more difficult to dissociate the cells in a healthy 

 condition. Or the failure of the plasmodial masses to go on and metamorphose may 

 be ascribed to a less hardy nature of this species-tissue. 



Experiment record, August 11, 1907. — Specimen from under laboratory pier was 

 cut up into pieces, and the pieces strained through bolting cloth into Minot watch 

 glasses. The sponge tissue comes out in clouds made up of cells and minute groups of 

 cells. Practically no skeleton is intermixed. As the tissue settles to the bottom, it is 

 shaken into center of watch glass, and is then strewn with pipette over cover glasses in 

 saucers. 



The tissue behaves quite as in the case of Microciona. The cells and small cell 

 groups display the same amoeboid phenomena, and attach to the glass. They fuse 

 and in the course of a day give rise to plasmodial masses, some rounded, some irregular, 

 others in the shape of networks, essentially as in Microciona. The plasmodial masses 



