Coalescence and Regeneration in Sponges 247 



another. After allowing time for the cells to settle and attach, 

 the water is poured off and fresh sea-water added. The tissue 

 is freed by currents of the pipette from the bottom and is col- 

 lected in the center of the saucer. Fusion betw^een the individual 

 cells has bv this time gone on to such an extent that the tissue now 

 exists in the shape of minute balls or cell conglomerates of a more 

 or less rounded shape looking to the eye much like small inverte- 

 brate eggs. Microscopic examination shows that between these 

 little masses free cells also exist, but the masses are constantly 

 incorporating such cells. The tissue in this shape is easily 

 handled. It may be sucked up to fill a pipette and then strewn 

 over cover glasses, slides, bolting cloth, watch glasses, etc. The 

 cell conglomerates which are true syncytial masses throw out 

 pseudopodia all over the surface and neighboring conglomerates 

 fuse together to form larger* masses, some rounded, some irregu- 

 lar. The details of later behavior vary, being largely dependent 

 on the amount of tissue which is deposited in a spot, and on the 

 strength of attachment between the mass of tissue and the sub- 

 stratum. 



Decidedly the best results are obtained when the tissue has been 

 strewn rather sparsely on slides and covers. The syncytial 

 masses at first compact and more or less rounded, flatten out 

 becoming incrusting. They continue to fuse with one another 

 and thus the whole cover glass may come to be occupied by a 

 single incrustation, or there may be in the end several such. If 

 the cover glass is examined at intervals, it will be found that 

 differentiation is gradually taking place. The dense homogeneous 

 syncytial mass first develops at the surface a thin membrane with 

 underlying connective tissue (coUenchyma). Flagellated cham- 

 bers make their appearance in great abundance. Canals appear 

 as isolated spaces which come to connect with one another. 

 Short oscular tubes with terminal oscula develop as vertical pro- 

 jections from the flat incrustation. If the incrustation be of any 

 size it produces several such tubes. The currents from the 

 oscula are easily observed, and if the cover glass be mounted in an 

 inverted position on a slide the movements of the flagella of the 

 collar cells may be watched with a high powxr (Zeiss 2 mm.). 



