124 



MANUAL OF ZOOLOGY. 



Sometimes the "gonangium" or "gonotheca" contains only 

 a single gonophore, but more commonly it contains several, 

 which increase in maturity as we recede from the base of the 

 gonoblastidion (or blastostyle) and approach its summit (fig. 

 47, B). The buds carried on the sides of the blastostyle may 

 have the form either of sporosacs or of medusoids. The ova 

 may be directly discharged into the surrounding water, or may 

 be retained for some time in a peculiar receptacle, " where 

 they undergo further development, and which is supported 



upon the summit of the 

 gonangium, and lies entire- 

 ly external to its cavity " 

 (Allman). 



In Plumularia and some 

 of its allies there occur cer- 

 tain peculiar structures, to 

 which the name of " nema- 

 tophores " has been applied. 

 Each of these consists of 

 a process of the coenosarc, 

 which is invested by the 

 horny polypary, with the 

 exception of the distal ex- 

 tremity,, which remains op- 

 en. The nematophores are 

 sometimes fixed, sometimes 

 movable. They " consti- 

 tute cup - like appendages 

 (fig. 49, n n) formed of 

 chitine, and filled with pro- 

 toplasm, which has the pow- 

 er of emiting pseudopodia 

 or amoeboid prolongations 

 of its substance, and hav- 

 ing their cavity in commu- 



Fig. 49. -Portion of a branch of Antennularia nication with that of the 



antennina, enlarged. (After Allman.) /One mmmrm tnhp rf fh^ hvrlrn 



of the polypites ; * nn Nematophores emit- COmmOll tUDC Ot tH6 nyClrO- 



ting pseudopodial filaments of sarcode ; n' cauluS (Allman). Whilst 

 Nematophore with its sarcodic contents p ,1 ~J~ ' .,^1 



quiescent ; c Coenosarc enclosed within the P ar t Of the SarCOOe in each 



polypary. nematophore is capable of 



being extended in long fila- 

 ments resembling the pseudopodia of an Amceba, another por- 

 tion is charged with large thread-cells, and is not capable of 

 emission in this way. The function of these extraordinarily 

 modified zooids is uncertain. 



