14 BULLETIN OF THE BUREAU OF FISHERIES. 



died. On other covers the networks gradually contracted so as to produce thicker 

 sheets of tissue. These in part were continuous and in part perforated with gaps which 

 represented the spaces of the earlier reticulum. The preparations died in this condi- 

 tion. On still another set of covers the plasmodial networks continued to contract, 

 and in the course of a couple of days had so contracted as to be in the shape of numerous 

 distinct, spheroidal masses, many of which were in the neighborhood of i mm. in diam- 

 eter. These, too, died after some days without further change. 



Experiment record, August 2 j, 1907. — Stylotellas were cut up and strained in the 

 usual way. Only the basal denser parts of the sponge were used. The tissue was 

 spread over the bottom of saucers (50 mm. diameter), and these were soon transferred to 

 large crystallization dishes of sea water. On the following morning the tissue covered 

 the bottom of the saucers partly in the shape of reticula, partly in the shape of con- 

 tinuous incrustations having a ridged and exceedingly irregular surface, and partlv as 

 small isolated masses of spheroidal or irregular shape. These various kinds of Plas- 

 modia developed no further, but gradually died. 



RESULT OF INTERMINGLING DISSOCIATED CELLS OF MICROCIONA AND LISSODENDORYX. 



As the following experiments show, when the dissociated cells of these two species 

 are intermingled, they do not fuse with one another, but fusion goes on between the 

 cells and cell masses of one and the same species. Perhaps if the mixture were made 

 under conditions such as those which make cross fertilizations possible that normally 

 will not occur, better success might be had. As I have said elsewhere," the more prom- 

 ising task is to find allied forms, the tissues of which will fuse under natural conditions. 



Experiment record, August 9, igoy. — Dissociated cells of Microciona prolifera and 

 Lissodendoryx carolinensis were prepared in the usual way in separate watch glasses. 

 In each case the cells and small cell masses began to fuse quickly. The bulk of the 

 tissue, including all the coarser masses, was then removed with a pipette from each 

 watch glass. There were thus left only the very smallest masses and separate cells 

 strewn over the bottom. These were dislodged with pipette and collected in center 

 of watch glass. The two collections of tissue, the one of Microciona, the other of Lisso- 

 dendoryx, were then brought together in the same watch glass, and were thoroughly 

 intermixed by use of the pipette. 



The Microciona tissue is bright red, the Lissodendoryx tissue greenish. The contrast 

 of color is very marked between masses of any size. Between cells or very minute cell 

 masses the difference in color is of course much less conspicuous. The mixture of tissues 

 in the watch glass was kept under constant observation, but the behavior of individual 

 cells and of the most minute cell masses was disregarded. The mixture of tissues was 

 spread evenly over the bottom of the watch glass, and looked like a fine sediment. 

 Fusion began, and the bottom was soon covered, no longer with a continuous "sediment " 

 but with discrete small masses, some red, some green. Pseudopodial activity was 

 observed at the periphery of both kinds. 



a Wilson, H. v.: On some phenomena of coalescence and regeneration in sponges, Journal of Experimental Zoology, vol. 



V, 1907, no. 2. p. 25,1. 



