THE LOWER FORMS OF LIFE. 



91 



like the tentacles and polypites, with thread cells, which the animal 

 can at will discharge, paralysing its victim or enemy. The 

 'Portuguese man-of-war," therefore, consists of a large bladder- 



a 



Fig. 114. A tentacle of P. ntriculus (a), as it is attached to its basal sac, 6. 



Fig. 115. One of the " thread cells " magnified. 



Fig. 116. The same after it has discharged its thread. 



Fig. 117. Diagram of Physophorid ; a, the pneumatophore ; b, the necto-calices ; c, the poly- 



pite and its tentacle ; d, the ccenosarc. 



like coenosarc containing a pneumatophore and its pneumatocyst. 

 From the coenosarc depend the polypites (c), the tentacles (b and d), 



