FOULING OF SHIPS' BOTTOMS 



201 



after attachment of a free-swimming larva, which changes its form completely upon 

 fixation and produces a stalked growth or stolon. In many forms this stalk branches 

 profusely and forms a treelike structure, often attaining a length of 6 or 8 inches. 

 (Fig. 7.) Here, too, the living animal is inclosed within a chitinous sheath, which 



"!1^ 



Fio. 6.— Larval stages in the development of barnacles and the condition of the antennae at the time of attachment. A, dorsal 

 view of the nauplian larva of Balanus perforatus (after Groom); B, cyprid larva of Tetraclita divisa (after Nilsson Cantell); 

 C, cyprid larva of Scapellum (after Nilsson CanteU); D, lateral view of a cyprid of Lepas fasiailatus, showing internal 

 anatomy (after Willemoes, as in Hoek) 



persists (especially in the case of Tubularia) for many months after the death of 

 the organism. Since these colonial organisms obtain their food by means of feeding 

 polyps, which are situated at the ends of the stalk or its branches, and since all 

 other parts of their bodies are protected by the chitinous TiydrotTieca, it is apparent 



