246 H. V. Wilson 



I again took up this question and am now in a position to 

 state that the dissociated cells of silicious sponges after removal 

 from the body will combine to form syncytial masses that have 

 power to differentiate into new sponges. In Microciona, the 

 form especially worked on, nothing is easier than to obtain by 

 this method hundreds of young sponges with well developed canal 

 system and flagellated chambers. How hardy sponges produced 

 in this artificial way are and how perfectly they will differentiate 

 the characteristic skeleton, are questions that must be left for 

 more prolonged experimentation. 



Taking up the matter where it had been left at the end of the 

 preceding summer, I soon found that it was not necessary to allow 

 the sponge to pass into a degenerative state, but that the fresh and 

 normal sponge could be used from which to obtain the teased out 

 cells. Again in order to get the cells in quantity and yet as free 

 as possible from bits of the parent skeleton, I devised a substi- 

 tute for the teasing method. The method adopted is rough but 

 effective. 



Let me briefly describe the facts for Microciona. This species 

 (M. prolifera Verr.) in the younger state is incrusting. As it 

 grows older it throws up lobes and this may go so far that the 

 habitus becomes bushy. The skeletal framework consists of 

 strong horny fibers with embedded spicules. Lobes of the sponge 

 are cut into small pieces with scissors and then strained through 

 fine bolting cloth such as is used for tow nets. A square piece 

 of cloth is folded like a bag around the bits of sponge and is 

 immersed in a saucer of filtered sea-water. While the bag is 

 kept closed with the fingers of one hand it is squeezed between the 

 arms of a small pair of forceps. The pressure and the elastic 

 recoil of the skeleton break up the living tissue of the sponge 

 into its constituent cells, and these pass out through the pores of 

 the bolting cloth into the surrounding water. The cells, which 

 pass out in such quantity as to present the appearance of red 

 clouds, quickly settle down over the bottom of the saucer like a 

 fine sediment. Enough tissue is squeezed out to cover the bottom 

 well. The cells display amoeboid activities and attach to the 

 substratum. Moreover they begin at once to fuse with one 



