DEVELOPMENT OF SPONGES FROM DISSOCIATED TISSUE CELLS. II 



i6 with figure 5, which represents a vertical section of a normal sponge, it will be seen 

 that the regenerated and normal specimens are essentially ahke. 



In regenerated sponges that are kept one or two months in the live box repro- 

 ductive bodies make their appearance. In some cases they are found strewn through 

 parts of the incrustation in great numbers, precisely as in the normal sponge. One of 

 these bodies is represented in figure 16. I have not worked out the origin of the repro- 

 ductive bodies, and so am unable to state whether they arise from eggs or masses of 

 cells. 



Some of the Microciona slide preparations that were kept one to two months in the 

 live box grew to be i mm. thick in regions, and developed lobular outgrowths such as 

 those on the sponges shown in figure 2, plate i. In a preparation before me such lobular 

 outgrowths vary in height from i mm. to 10 mm. and in thickness from i mm. to 4 mm. 



It is clear from the preceding account that Microciona can be perfectly regenerated 

 by this method of growth from dissociated cells. 



The question may arise how large or how small a mass of the plasmodial syncytial 

 tissue will transform into a sponge. The question would seem to be a purely physio- 

 logical one, for the idea of morphological individuahty is not appUcable to the plas- 

 modial tissue nor indeed even to the sponge itself. Fusion or subdivision may con- 

 stantly occur both among the plasmodia and in the case of the perfected incrusting 

 sponge, whether large or of microscopic size. 



The upper limit to the size of incrustations formed by the fusion of plasmodia is 

 obviously not determined by intrinsic laws of differentiation, but by the success or 

 absence of success with which the different regions of each incrustation meet in the 

 struggle for food and against enemies. 



The lower limit can not be stated. Small plasmodia, instead of fusing, may flatten 

 and metamorphose into tiny sponges only a fraction of a millimeter wide. The two 

 cover-glass preparations represented in figures 18 and 20 show numerous such small 

 Plasmodia. Experience in rearing sponges grown in this way shows that the very little 

 ones are at a disadvantage. They frequently die and disappear when larger incrusta- 

 tions under the same conditions continue to live and grow. There must of course be a 

 lower limit to the size of the tissue mass which can directly (without further growth) 

 transform into a sponge having osculum, canals, flagellated chambers, etc. Doubtless 

 a mass of tissue below a certain minimum and outside the body of the parent could only 

 become part of a perfect sponge by fusing with some other mass. Inside the body of 

 the parent such a mass would have the ordinary opportunity of growth that falls to the 

 lot of metazoan cells, and conceivably might increase of itself to the size of an asexual 

 reproductive mass (gemmule). 



USSODENDORYX CAROLlNENSIS. New Species. 



DESCRIPTION OF SPECIES. 



This sponge is common in Beaufort Harbor under the wharves. Habitus changes with age. 

 Sponge exists first as a thin incrustation on shells, piles, etc. With continued growth it throws up 

 ascending lobes 10-20 mm. high, which frequently overlap in an intricate way. Eventually a large, 

 amorphous mass may be produced, incrusting at its base but the body of which has been formed by the 



