910 THE ANIMAL KINGDOM. 



to form spores. This it does, either on the outer surface of a sporospore 

 s. conidiophore, as in the Exosporea, or as in the Endosporea, within one 

 or more sporocysts or sporangia, which are derived in most instances 

 from a single plasmodium, but in a few, e. g. Fuligo, from a number of 

 united plasmodia, or, as they are termed, an aethalium. 



In Ceratium, the sole genus of Exosporea, the plasmodium first collects 

 into a mass, and then grows up into a number of processes or conidio- 

 phores. Mass and processes alike are formed of a watery jelly supporting 

 a network of granular protoplasm. This network traverses the whole 

 substance of the mass ; it passes into the processes as they develope 

 and in them is confined to a superficial layer. It is finally resolved into 

 polyhedral cells. Each cell grows out into a stalked sphere, protected 

 by a delicate membrane. The protoplasm is concentrated by degrees in 

 the sphere, which is converted into a spore by the development of a special 

 membrane. The spores are detached with ready ease from their stalks, and 

 the supporting jelly dissolves as soon as it is function-less. 



The plasmodium of the Endosporea gives origin to a single sporocyst, 

 or by division to many. It gathers together, developes a superficial coat 

 or membrane, and extrudes at the same time all foreign bodies, pigment 

 and Calcium carbonate if present 1 . The resulting sporocyst has generally 

 the shape of a sessile or stalked vesicle ; in a few instances it is tubular, 

 slightly branched, or even reticulate, and then frequently receives the name 

 of plasmodiocarp. It is attached to whatever it rests upon by the dried 

 mucoid envelope or hypothallus, which forms either a thin flat expansion, 

 a ridge, or peduncle. The protoplasm, freed from whatever is foreign to 

 it, is colourless, and from it are derived the capillitium and the chlamydo- 

 spores. The former consists of 'either stereonemata or coelonemata 

 stereonemata, that is to say cords cylindrical or flattened, solid, or at the 

 utmost traversed by a fine canal ; coelonemata, or tubes with thin walls 

 and wide cavities. Both structures consist of a cuticularised membrane, 

 and the stereonemata of the Calcariaceae include pigment and Calcium 

 carbonate. As to the mode in which the capillitium is disposed, the 

 stereonemata are either variously shaped thickenings of the walls of the 

 sporocyst 2 , or they are branching strands crossing its cavity and attached 

 by their ends to its walls ; the coelonemata take one of three forms, tubes, 

 or elaters, closed at their ends and lying free as in Trichiaceae^ a narrow- 

 meshed expansile reticulum with its ends attached to the walls of the 

 sporocyst, as in most Arcyriaceae and the Perichaenaceae, or a branched 

 structure with the cavity of its constituent tubes varying in width from 

 point to point, as in the Reticularaceae and Lycogala among Arcyriaceae. 



1 In Didymium the Calcium carbonate dissolves, and reappears on the outer surface of the 

 sporocyst as a crystalline deposit. 



2 De Bary does not apply the term capillitium to these thickenings. 



