8 DIVERSIONS OF A NATURALIST 



the little polyp which it had been my chief object to 

 study, issued slowly from its delicate tubes when placed 

 in a shallow trough of sea-water beneath the microscope. 

 I was able on that day, and many others subsequently — 

 with renewed supplies from the depths of the fiord — to 

 make coloured drawings of it, and to find out a great deal 

 of interest to zoologists about its structure. The minute 

 thing (Fig. 2) was spotted with orange and black like a 

 leopard, and had a plume of tentacles on each side of its 

 mouth, which was overhung by a mobile disk — the organ 

 by means of which it creeps slowly out of its tube, and 

 also by which the transparent rings which form the tube 

 are secreted and added one by one to the tube's mouth, 

 so as to increase its length. The creature within the tree- 

 like branching system of tubes (Fig. i ) is also tree-like and 

 branching, fifty or more polyp-like individuals terminating 

 its branches and issuing each from one of the upstanding 

 terminal branches of the tube system. I was able to 

 determine the " law " of its budding and branching, and 

 I also found the testis full of spermatozoa in several of 

 the polyps, but I failed to find eggs. I believe that we 

 were too late in the season for them ; and they are still 

 unknown. 



One of the most interesting deep-sea creatures dis- 

 covered by the " Challenger " proved to be closely allied 

 to our little Rhabdopleura, and received the name 

 " Cephalodiscus." Several species of this second kind 

 have been discovered in the last twenty years in the 

 deep sea, and the largest and most remarkable in some 

 respects was one which " jumped to my eyes " among 

 the booty of marine dredgings sent home from the 

 Antarctic expedition of the " Discovery " by Captain 

 Scott, when I unpacked the cases containing these 

 marine treasures, in the basement of the Natural History 



