THE GONOSOME. 



Fig. 2S. 



of a poppy. They vary in number ; I have counted in the female from eight to sixteen or twenty. 

 They are composed of ectoderm and endoderm, the ectoderm containing thread-cells, and the 

 endoderm presenting the usual sep- 

 tate appearance. They are less 

 numerous and less developed in the 

 male than in the female. 



The contents of the sacs are, 

 as in an ordinary gonophore, either 

 ova or spermatozoa, and the sexes 

 are invariably found separated on 

 distinct colonies. The ova, while 

 contained within them, pass through 

 the various stages of development 

 up to that of ciliated embryos, in 

 which state, as has been already 

 shown by Loven, they are discharged 

 into the surrounding water through 

 the orifice in the summit. 



If we follow the development 

 of these extracapsular gonophores, 

 we shall find, as, indeed, Loven had 

 already pointed out, that they are 

 originally produced within the go- 

 nangium where they originate, ex- 

 actly like intracapsular gonophores, 

 as buds from the blastostyle. By 

 the growth of the blastostyle the 

 gonophores are carried upwards with 

 it, in the order of their maturity — 

 the oldest ones, while within the 

 gonangiinn, being always nearest the 

 summit of the blastostyle ; but in- 

 stead of discharging their contents 

 and then withering away on their 

 arrival at the orifice of the gonan- 

 gium, as in ordinary adelocodonic 

 forms, they are here carried out 

 through the orifice, become truly 

 extracapsular, and in this state un- 

 dergo, with their contents, further 

 development, while the growing 



blastostyle alwaVS keeps its extremity "^^ ™°'''^ advanced meconidium ; /, radiating canals, united by the c 

 "^ "^ n ; m, ovum with germinal vesicle and spot; o, o, embryos, escapin? 



truncated on a level with the summit of ciliated piauuia;. 



of the gonangium, whose orifice it continues to close by a plug-like expansion, which at the same 



Gonangium with Meconidin of OonothyrtBa Loveni (female). 

 a. Cavity of gonangium; b, b, blastostyle, with c, its opercular summit; 

 d, d', d'\ gonophores in various stages of maturity still within the gonangium, 

 all surrounded by the gubernacular membrane; in d" the tentacles are seen 

 already formed and lying back on the walls of the gonophore; g^g't meconidia, 

 g' being more advanced tlian g ; e, mesotheca, external to which may be seen the 

 ectotheca loaded with thread-cells ; Jc, endolheca ; k\ remains of endotheca in 



rcular canal, 

 in the form 

 of ciliated plauulEe. 



