214 SEAWEEDS 



Gdidiece. 



The gonimoblast consists of much-extended, diffuse 

 filaments which frequently unite with the thallus 

 cells, these being in some cases specially developed 

 as auxiliary cells. The terminal, carpospore -bearing 

 cells occur in fertile sori or groups (like the hymenial 

 layers of fungi), and bear the spores singly as a rule, 

 rarely in short chains. The main difference between 

 this type and the preceding families lies in the fact 

 that this gonimoblast is not nourished exclusively by 

 the fertilised carpogonium, but attaches itself in this 

 growth to other cells, viz., cells of the thallus-tissue. 

 A single gonimoblast is produced as a rule, but it 

 ramifies abundantly, and lays under contribution 

 either cells of the central axial row or the small- 

 celled tissue that envelops it. From the ends of 

 the branches of the gonimoblast the carpospores are 

 produced, as described. During the branching of 

 the gonimoblast a local enlargement of the thallus 

 occurs, and within this the cystocarpic fruit is 

 developed, with no special wall of its own, and 

 bounded only by the sterile thallus-tissue. An 

 opening is formed by the separation of the peripheral 

 cells, through which the carpospores escape. In 

 Naccaria the carpogonial branch exhibits a difference 

 from the ordinary type. From the cells composing 

 this branch short lateral branches arise, and the whole 

 constitutes a definite system of cells. The carpo- 

 gonium itself is relatively a small one, but before 

 emitting the gonimoblast it unites with one of the 



