CRUMB SPONGES. 257 



and clean sea-water, and left for twelve hours at least. 

 Then, taking care not to touch the glass cell, nor to 

 jar even the table on which it is placed, either of 

 which might cause the sensitive sponge instantly to 

 cease its operations, we bring a powerful pocket-lens 

 close to the glass, and intently watch the specimen 

 within. Suppose it is one of the yellow species, which 

 throws up little hillocks, the Crumb-of-bread Sponge; 

 our attention is at once excited by seeing a strong 

 movement in the water, through which tiny atoms are 

 hurried along in swift currents. We fix our gaze on 

 one of the hillocks : lo ! it is a volcano indeed ! 

 From the perforate summit of the cone, as from an 

 active crater, is vomited forth a strong and continuous 

 stream of water, and crowds of atoms come pouring 

 forth, disgorged in succession from the interior, and 

 projected far away into the free water, to be followed 

 by unintermitting crowds of others. This is highly 

 curious, and we wonder what is the nature of the 

 power which so strongly conveys to us the idea of an 

 active vitality in a mass so inert and apparently life- 

 less as this yellow encrusting sponge. 



But let us apply the magnifying glass to another 

 cell containing one of the bits of rock that has on it 

 the cones of pellucid rosy lilac, the Kosy Crumb 

 Sponge. There is a general resemblance to the for- 

 mer in shape, as it is an encrusting kind, spreading 

 over the stone, and rising here and there into well- 

 marked conical eminences, each of which is perforated 

 with a large circular orifice. The colour somewhat 



it 



