98 



BOYS AND GIRLS IN BIOLOGY. 



the microscope, you will find other stripes, or bars, go- 

 ing crosswise (Fig. 96). These two sets of lines make 

 a lattice-work, which forms the sides of the pocket, and 

 over this lattice-like framework is stretched a thin skin, 

 which is all filled with little blood-vessels. The open- 

 ings of the lattice-work are all surrounded by very 

 strong moving cilia, or lashes (Fig. 96), like those we 



Fig. 96. 



A Piece of the Gill-Pocket, showing Blood- Vessels, Framework, and Cilia. 



saw around the two openings of the mantle — the dor- 

 sal and ventral siphons. The cilia, or lashes, are 

 always moving, and as they work they lash the water 

 through the openings of the lattice-work into the pock- 

 ets of the gills (Fig. 95), and out again by the door 



