o o 



88 EVENINGS AT THE MICROSCOPE. 



arrangement discernible here ; for the canals are formed 

 by the manner in which these are grouped ; and this is 

 seen much more clearly in the case of the three-rayed 

 needles of lime in the Grantice. Mr. Bowerbank has 

 shown that in G. compressa the substance is divided 

 into very regular chambers in a double series, divided 

 by a diaphragm, whose axis is at right angles to the 

 axis of the sponge ; and that these chambers are denned 

 by walls made up of the three-rayed needles in their 

 mutual interlacement. 



