Coalescence and Regeneration in Sponges 257 



in contact two masses of the same specific protoplasm tend to 

 fuse. This tendency is probably useful (/. e., adaptive) in that 

 the additional safety (from enemies and "accidents") accruing 

 from increase in size of the mass more than compensates- for 

 the reduction in number of the individual masses that start to 

 grow (rearing of sponges shows that masses of good size frequently 

 withstand conditions that effectually wipe out the very small 

 masses). Unlike specific substances (protoplasms of quite dif- 

 ferent species) do not tend to fuse. 



To the many biologists who have found ideas and observations 

 of deep interest in the papers on protoplasmic activities by Pro- 

 fessor and Mrs. E. A. Andrews (G. F. Andrews), the statement 

 just made will have a familiar sound. Mrs. Andrews in her essay 

 on The Living Substance as Such and as Organism'^ and her 

 paper on The Spinning Activities of Protoplasm^" makes, it would 

 appear from subsequent confirmations, a definite advance in our 

 knowledge of the intimate structure of protoplasm. But it is her 

 generalizations, based on singularly acute observations, with 

 respect to the behavior of protoplasm, that have especially influ- 

 enced my own work. The particular generalizations referred to 

 may be so formulated: 



1 Protoplasm tends to produce a viscous, pellicular layer with 

 formation of pseudopodial outgrowths over the surface, whether 

 external or internal to the mass, which establishes contact with 

 the environmental medium. 



2 Pseudopodia from adjacent masses of the same specific 

 substance tend to fuse. Thus actual connections which can be 

 made and remade, and along which transference of substance 

 takes place, are established between the masses. 



That these phenomena are observable in w^idely separated 

 groups of metazoa has been also shown by Professor Andrews in 

 a series of brief studies marked with his well known skill and 

 accuracy of observation and statement. I fully agree with him 

 as to the great importance of the facts. 



The general point of view entertained by Mrs. Andrews in her 



^ Suppl. to Journ. Morphology, vol. xii, no. z, 1897. 

 ^"Journ. Morphology, 1897. 



