64 



HALF AN HOUR WITH SPONGES. 



branches rounded or compressed and the surface even. 

 As before observed, the oscula are arranged in lines, 

 more or less on one side each branch. The margins 

 of these orifices are slightly elevated, but scarcely 

 noticeable. In the outer membrane may be found 

 a few slender, needle-like spicules, but those of the 

 interior, or skeleton, are shorter and stouter, and 



Fig. 26. 



Section of Chalina oculata. 



rather spindle-shaped. When this sponge is living, 

 it is of a yellowish colour, with just a tinge of green. 

 It changes rapidly after being uprooted, and passes 

 into the usual colour of common sponge when dried. 

 Fig. 26 will give our readers a good notion of the 

 appearance of a portion of a section of this sponge 

 under the microscope. There they will see the 



