274 



PART IV. CLASSIFICATION. 



sporangia, or filaments bearing sporangia, are formed. In other 

 cases the carpogonium gives rise to one or more elongated, branched, 

 ooblastema-filaments which fuse with one or more auxiliary cells, 

 and the sporangia are produced either from the ooblastema- 

 filaments (e.g. Gelidiacese) or from the auxiliary cells (e.g. Squama- 

 riacese and other Cryptoneminse). 



In the Corallinacese, where the procarps are aggregated in re- 

 ceptacles, only a single cystocarp is formed from the whole group 

 of procarps. Some of the procarps appear to be altogether abor- 

 tive, and only those toward the centre of the group have tricho- 

 gynes, whilst others seem to have only auxiliary cells : after 



Fio. 161. Sexual organs of Spermothamnion Hennaphro&itwn. A Male and female organs ; 

 c multicellular procarp ; t trichogyne ; V trichophore ; on terminal cluster of antheridia. 

 B cystocarp developing from the fertilised procarp ; a cluster of carposporangia is 

 springing from each of the two opposite lateral auxiliary cells. The development of the 

 cystocarp is indirect ( x 300 ; after Naegeli). 



fertilisation, the carpogonia of the central procarps fuse with 

 each other, and with the auxiliary cells of the other procarps, 

 forming a large cell from the periphery of which the corpo- 

 sporangia, constituting the cystocarp, are developed. 



In many cases the cystocarp consists merely of the cluster of 

 sporangia (e.g. Bangia, Chantransia, Callithamnion, Dudresnaya) ; 

 in other cases the cluster of sporangia is surrounded by a cellular 

 investment, termed the pericarp, formed by the growth of adjacent 

 sterile cells. 



Each sporangium always gives rise to a single carpospore, which 



