ON THE CYSTOCARPS OF CATENELLA OPTJflTIA. 75 



young cystoearpic ramuli whose trichogynia had not been fer- 

 tilized, that his interpretation of these as sterile vegetative cells 

 is correct. He adds fin a letter to me), " Solche vegetative 

 Zellen werden bei vielen Florideen wahrend der Cystokarp- 

 entwicklung im Frucht-Spross neugebildet (z. B. bei Gelidium, 

 Gloiopeltis, u. s. w.) oft durch Zellvermehrung aus den unbe- 

 fruchteten Carpogonasten." Fig. 8 represents such a complex 

 of sterile vegetative cells surrounding a trichophoric apparatus. 



Fertilization is effected by the fusion of the pollinoids released 

 from the antheridia with the trichogynia. The majority of the 

 tricbogynia are so fertilized. Each trichogyne is, as has been 

 already show r n, in direct communication by means of the tri- 

 chophoric cell (or cells) with the subcortical weft of hyphae, 

 which is in turn continuous with the longer and larger medullary 

 cells. When fertilization is complete, the development of carpo- 

 spores commences. The uppermost of the central row of cells 

 of the ramulus enlarges very considerably, and from it, as well as 

 from the network of hyphao surrounding it (and with which it is 

 connected at many points), there are given off rows of rounded 

 or ovoid cells (carpospores) much larger and more granular than 

 those which (mixed with them) give origin to the rind-cells. By 

 continued growth of these branched chains the subcortical reti- 



culum is separated and the meshes become filled with carpospores, 

 between which the sterile filaments pass to the periphery. The 

 larger cell of the central axis in a transverse section of an old 

 cystocarp shows itself to be yellowish, granular, branched, and 

 connected on all sides with the network of filaments from which 

 the carpospores arise (PL XIV. fig. 12). 



There is no carpostome, and doubtless the spores escape by 



rupture of the rind and cuticle, the latter already weakened by 



the numerous apertures occurring in it through which the tri- 

 cbogynia pass to the exterior. 



It will be seen, then, that the mode of formation of the cysto- 

 carp in C. Opuntia differs in many poiuts from the more usual 

 Floridean type. In the first place, although the trichophoric 

 systems are very numerous, only one cystocarp is produced. 

 Further, fertilization is indirect ; for instead of the carpospores 

 being produced from the cells immediately beneath the trichogyne, 

 they are developed in chains from the medullary network of cells 

 continuous with that from which the trichophoric cells and tricho- 

 gynia arise. There can be no doubt, however, that the processes 





