l6 BULLETIN OF THE BUREAU OF FISHERIES. 



quantities in a dish of sea water, as soon as possible after the extrusion of the cells, and 

 while only separate cells and fine cell masses existed. 



The mixture was then quickly strewn with pipette over eight cover glasses immersed 

 in sea water. The formation of small compact masses, some red, some greenish, in 

 about equal number, ensued. These grew by fusion with their own kind. After a 

 couple of days the Microciona plasmodia were thriving, but the Lissodendoryx masses 

 had decreased in quantity. 



By August 12 the condition of one of the covers was as follows: The Microciona 

 masses were thin and incrusting and had begun to metamorphose, viz, had flagellated 

 chambers. The Lissodendoryx tissue was in the shape of compact masses, many now 

 beginning to disintegrate, but others spheroidal, smooth, and healthy looking. In 

 places small spheroidal masses of Lissodendoryx tissue remain embedded in the metamor- 

 phosed Microciona. The total amount of Lissodendoryx tissue is very small as compared 

 with that of Microciona. 



The second cover-glass preparation was on August 12 for the most part like the 

 one just described. But in exceptional places the condition was that shown in figure 28, 

 where the Lissodendoryx tissue is again represented by stippled and the Microciona tissue 

 by unstippled areas. The Lissodoidoryx tissue forms a somewhat large, flattened, 

 but not very thin mass, which is evidently still in the original dense syncytial condition. 

 On it the Microciona tissue has settled in the shape of spheroidal masses, also in original 

 dense syncytial state. Near by a partially metamorphosed Microciona plasmodium is 

 shown. Here there has evidently been a relatively long-continued opportunity for 

 fusion between the dense syncytial masses of the two species, but no fusion has occurred. 

 By August 16 the Microciona masses have flattened out over the underlying and still 

 unchanged Lissodendoryx, and have in part fused with one another. 



The remaining cover-glass preparations of this set on August 12 oS'ered nothing 

 different from conditions found on the two covers just described. On August 16 they 

 were all about alike, the Microciona plasmodia metamorphosed, the Lissodendoryx masses 

 still unchanged. Small compact masses of the Lissodendoryx tissue are found here and 

 there in the metamorphosed Microciona. They probablv die and disintegrate. 



RESULT OF INTERMINGUNG DISSOCIATED CELLS OF MICROCIONA AND STYLOTELLA. 



In endeavoring to bring about fusion between these two kinds of tissue, the same 

 methods were followed and essentially the same results were obtained as for Microciona 

 and Lissodendoryx. The cells and cell masses of each species tissue fused with one 

 another, and there was an absence of fusion between the tissues of the two species. The 

 Stylotella tissue is brown and easily distinguishable from Microciona tissue. 



The following experiment on plasmodia] masses of some size is recorded as perhaps 

 of value for guidance in future work : 



Experiment record, Atigusl 26, igoj. — Plasmodia] masses of Microciona and Sty- 

 loklla were placed in contact about 9 p. m., to test whether they would fuse. The 

 Microciona plasmodium was of reticular character and had begun to curl up round the 



