A BIT OF SPONGE. 



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the whole history of life. This morning, we cannot 

 do better than follow in the footsteps of the child, and 

 to the question, " What is a sponge ? " I fancy science 

 will be able to return a direct answer. 



First of all, we may note that a sponge, as we know 

 it in common life, is the horny skeleton or framework 

 which was made by, and which supported, the living 

 parts. These living parts consist of minute masses 

 of that living jelly to which the name of protoplasm has 



Fig. 18. Development of a Sponge (Olynthus). 



i, The egg ; 2, 3, and 4, the process of egg-division ; 5 and 6, the gastrula- 

 stage ; 7, the perfect sponge. 



been applied. This, in truth, is the universal matter 

 of life. It is the one substance with which life every- 

 where is associated, and as we see it simply in the 

 sponge, so also we behold it (only in more complex 

 guise) in the man. Now, the living parts of this dried 

 cast-away sponge were found both in its interior and 

 on its surface. They lined the canals that everywhere 



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