106 THE OCEANIC HYDROZOA. 



These bodies attain a diameter of one sixteenth of an inch or more. 



5. The androphores (fig. 14) commence as papillary elevations of the lateral walls of the 

 branches of the gonoblastidia, whose endoderm rapidly thickens, and consists of pale, circular 

 granules ^^^th of an inch in diameter. A small, csecal prolongation of the central cavity next 

 extends up one (or probably both) sides of the organ (fig. \4b). 



When these rudimentary androphores have attained a length of about T^h of an inch 

 (fig. 14 c), they are more completely pedunculated. The canal of the peduncle sends a short, 

 broad process, in the middle line, into the thickened apical mass, which now consists of two 

 portions — an inner membranous wall, resembling in all respects, and, apparently, continuous 

 with, the endoderm of the peduncle, and an outer thick mass lying between this and the 

 ectoderm, which consists of an aggregation of pale, spherical granules rr^th of an inch in 

 diameter. Two narrow, opposite canals pass from the upper end of the cavity of the peduncle, 

 and run close to its outer wall to terminate in blind ends. 



Finally, the organ increases in size, and its contents assume more and more the form of 

 spermatozoa (fig. 14 d). 



I can produce no direct evidence of the fact, but I entertain little doubt that the gyno- 

 phores are detached as free swimming medusiform zooids, as in Felella, and only develope their 

 ova subsequently. The androphores, on the other hand, must dehisce while still attached. 

 It might seem at first as if this arrangement were not very well calculated to ensure the 

 impregnation of the ova, but when we consider in what enormous troops the Pln/salicB 

 are ordinarily found, the difficulty disappears. 



All my Physdlim were taken either in the South Atlantic or in the Indian Ocean. 



