34 8 DISCOVERY REPORTS 



Riemsdijk. They found that the ultimate branchlets consisted of two divisions, one bearing a jelly- 

 polyp* and palpon, and the other a nectophore and palpon, and both bearing gonophores. 



My study of the morphology and development of the gonodendra of Physalia substantiates the work 

 of Lens and van Riemsdijk and amplifies it. I find that each normal final branchlet of the fully formed 

 gonodendra consists of two sections, which are very likely homologous, each carrying one palpon and 

 numerous gonophores (reduced sexual medusoids). The two sections can be distinguished from 

 one another because the terminal one has a jelly-polyp (jp) at the base of the palpon (pt), whereas the 



/ ^ J GONOZOOID 



if PALPON 



JELLY POLYP 



Text-fig. 25. Physalia physalis. A young gonodendron after removal of three branches. Specimen, Lanzarote no. 2. The 

 numerals refer to the number of subterminal, nectophore-bearing sections (not shown) on each end branch, x 9. 



sub-terminal section has a long-stalked nectophore («) in this position. The terminal palpons with 

 their jelly-polyps are visible in the earliest growth-stages of the gonodendra (PI. XXII, fig. 4) ; in well- 

 developed specimens the oldest terminal palpons at the bases of the larger gonodendral branches reach 

 a considerable size (Text-fig. 25). 



No further budding occurs from a terminal section. Growth of the gonodendra proceeds by buds 

 zvhich develop on the sub-terminal sections and which give rise by dichotomy to a successive series of 



* The jelly-polyp was called by Chun (1897a) and Steche (1907) the 'Gallert-polypoid'. It develops characters closely 

 resembling in some ways those of the nectophore or asexual medusoid (see page 351). 



