2 2 BULLETIN OF THE BUREAU OF FISHERIES. 



Fresh Microciona was teased up. The teased-out tissue was brought together so 

 that many small spheroidal masses were formed free of all fragments of the old skeletal 

 framework. About a dozen such masses were then brought together with needle and 

 pipette. They fused, giving rise to the lobed mass shown in figure 27. The width of 

 the whole mass is slightly less than i mm., the thickness about 0.5 mm. It contains no 

 skeletal fragments, although close at hand lies a bit of the old skeletal framework. 

 The outlines of the lobes gradually disappeared and on the same day the mass had 

 assumed a simple rounded, subspheroidal shape. It incorporated the outlying piece 

 of skeleton and made attachment at points of the periphery to the substratum. Before 

 the end of the day the peripheral part of the body was extended out over the glass in 

 the shape of a thin sheet, showing pseudopodial activities at its edge, where the incor- 

 poration of outlying cells and small masses went on. Doubtless this preparation would 

 have completed the metamorphosis had it been kept. 



Experiment record 9, July 30, J907. — Result: Teased-out tissue strewn over cover 

 glasses formed plasmodia which metamorphosed completely. Pressed-out tissue 

 behaved in similar way. 



Fresh Microciona tissue was teased out and centripetalized in watch glass, and then 

 strewn over cover glasses. Small masses were formed which flattened and fused and 

 soon formed a continuous thin plasmodial sheet. The covers were kept in laboratory 

 dishes of filtered sea water, and the water was changed several times a day. On August 

 4 flagellated chambers were distinct and the flickering movement of the flagella could 

 plainly be seen with a Zeiss 2 mm. objective. By August 5 well-developed canals were 

 present, and oscula on short upwardly projecting tubes. The discharge of the current 

 from the oscula was watched. On August i pressed-out tissue obtained by straining 

 through bolting cloth was prepared and treated in same way with same result. 



Experiment record 10, August i, 1907. — Result: Pressed-out tissue, when it is 

 strewn thickly enough to form plates, etc., 0.5 to i mm. thick, does not transform in 

 laboratory aquaria, but the tissue tends to separate from the substratum and contract 

 into massive shapes. Such collections of tissue will transform in the open water. The 

 firmer the attachment to the substratum, the greater is the chance which the collection 

 of tissue has of metamorphosing. 



Pieces of Microciona were strained through bolting cloth. The tissue thus pressed 

 out was strewn thickly over fine bolting cloth fastened to coarse galvanized wire netting 

 and immersed in dishes of sea water. Irregular plasmodia formed which combined 

 for the most part into fine networks, such as that shown in figure 23, a. Isolated masses, 

 rounded or irregular, such as b in figure 23, were also formed. By the next morning the 

 Plasmodia had changed their character. Concentration of the tissue toward separate 

 centers had occurred, and thus the fine networks had broken up into coarser networks, 

 perforated plates, and more or less compact masses. \'arious such collections of tissue 

 are represented in figure 23, c-j. They are all in the neighborhood of 0.5 to i mm. 

 thick and adherent to the cloth. The tissue has considerable rigidity, although without 

 skeleton. Thus it may project up in shape of vertical lobes i mm. high, or as vertical 



