256 H. V. Wilson 



Fusion begins soon and the larvae are gradually converted into a 

 flattened cake. The larger cakes thus made measured four by 

 three millimeters. The body of such a cake is a continuous 

 flattened mass in which there is no indication of the component 

 larvae, but the rounded ends of the larvae that have last fused v^ith 

 the general mass remain for a time distinguishable. Owing to 

 their blue coloration the ends of the larvae may be recognized in 

 these and the other compound masses even after the outline of 

 the larva has been completely lost. 



As already stated the smaller compound masses metamorphose 

 without difficulty. The coalesced larvae may be made to attach 

 to cover glasses, slides, etc. Larger masses composed of about 

 twenty larvae underwent a partial metamorphosis. Such masses 

 were laid upon bolting cloth to which they readily attached. The 

 largest masses were hung in small bolting cloth bags in a live box. 

 Whether owing to bad handling or more probably to some inherent 

 difficulty, thev did not metamorphose but soon died. 



The ease with which larvae of the same species may be made to 

 fuse together suggests that larvae of diff^erent species might like- 

 wise be induced to coalesce. Some experiments along this line 

 could not fail to be of interest. 



IV 



In the tendency to fuse with the production of a plasmodium, 

 the dissociated cells of sponges resemble the amoebocytes (amoe- 

 bulae) of the mycetozoa and Protomyxa. The regenerative power 

 of the Plasmodium has an interest both theoretical and economic 

 in itself. But it is the tendency to fuse displayed by the cells that 

 have been forcibly broken apart, which constitutes the fact of 

 most general physiological importance. Discarding for the mo- 

 ment the word "cell" and speaking of the protoplasm of a species 

 as a specific substance, the phenomena may be restated to advan- 

 tage in the following way. 



A mass of sponge protoplasm in the unspecialized state typically 

 exhibits pseudopodial activities at the surface. In lieu of more 

 precise knowledge it is useful to regard the pseudopodia as struc- 

 tures which explore and learn about the environment. Oncoming 



