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H. V. Wilson 



several larvae unite to form a single sponge "which has from the 

 start several cloacas." 



I find that this power to fuse displayed by the larvae is one that 

 is easy to control. Fusion between larvae will readily take place 

 if they are brought in contact at the critical time when the ciliated 



Figs. I, 2, 3, 4 Composite masses produced by the fusion of larvae. The stippled ends and areas 

 are in nature blue, and represent the ends of the component larvae. The body of the mass is white. 

 Fig. I shows a mass composed of four larvae which has just united with a mass composed of five or 

 six larvae. In Fig. 2 more than ten, probably about twenty, larvae have combined. In Fig. 3 about 

 six larvae have combined. In Fig. 4 the original quadruple mass composed of four radiately arranged 

 larvae, has been extended in one direction by the addition of a pair of larvae, and in the opposite 

 direction by the addition of two pairs of larvae. Figs, i and 3 X 44; Figs. 2 and 4 X 22. 



epithelium is being replaced by the permanent flat epithelium. 

 At this time they will fuse in twos or threes or in larger number 

 up to and over one hundred (Figs. 1-4). The smaller composite 

 masses composed of as many as five or six larvae metamorphose 

 into perfect sponges. The larger masses composed of many 



