On the Pithophorace^e. 



17 



In by far the greatest part of sporiferous individuals, the spores 

 are brought forth in all parts of the cauloid, and in almost all the cauloid 

 cells. For these individuals I have employed the name fertile (pi. 2, 

 fig. 1, 2, 3, 13). But in some sporiferous individuals we find, that 

 spores are developed only in one part of the cauloid, while the other 

 parts consist of cells which never develop spores. These individuals 

 may be called half-fertile-half -sterile (pi. 2, fig. 6, 7). And the 

 individuals in which no spores at all are ever developed, are the sterile. 

 In the account of the construction of the vegetative system I have indi- 

 cated (page 7), that another difference does also exist between the fer- 

 tile and the sterile specimens, than the one consisting in the presence 

 or absence of spores. We recollect that this difference, in short, consists 

 in the circumstance, that the system of ramification is stronger developed 

 in sterile than in fertile specimens. If we observe the half-fertile-half- 

 sterile specimens somewhat nearer, we shall find that they are perfect 

 connecting forms between the sterile and the fertile. The sporiferous 

 part of the cauloid of the half-fertile-half-sterile specimens has a more 

 feebly developed system of ramification, resembling that which is found 

 in purely fertile specimens; the part which is not sporiferous has, on 

 the contrary, a more strongly developed, resembling that of purely 

 sterile specimens. Fig. G and 7 on pi. 2 represent two half-fertile-half- 

 sterile specimens of P. kewensis nob. In the specimen represented fig. 

 6 the upper part is fertile and the lower sterile; in the specimen repre- 

 sented fig. 7 the lower part is fertile and the upper sterile. In both 

 specimens, a very considerable difference exists between the system 

 of ramification of the fertile and of the sterile parts. While the fertile 

 part has short and few branches (several of the cells in the principal 

 filament are branchless), the sterile part has comparatively long 

 and numerous branches (all the cells of the principal filament carry 

 at least one branch, and in the specimen represented fig. 7 we find 

 several which carry two). — In the same manner as in P. kewensis nob. I 

 have found half-fertile-half-sterile specimens in other species of Pithophorece. 



Although the sterile specimens do not develop spores, still they 

 are not quite denied the possibility of reproduction. They have the 

 power to develop another kind of reproductive cells, the so-called pro- 

 lific cells. These cells are originated by common vegetative cells in 

 the following manner: some vegetative cells, very rich in chlorophyll, 

 absorb food in a more abundant quantity than the others, and store up 

 this food in themselves in the shape of granules of starch (pi. 3, fig. 



Nova Acta Reg. Soc. Ups. Ser. III. 3 



