6 A. E, HILTON ON CAPILLITIA OF MYCETOZOA. 



or to a central columella — they may be solid or tubular — simple 

 and unbranched — sparingly forked or freely branching — or 

 branching and anastomosing into a network superficial or 

 otherwise — and this network may be either inelastic or expan- 

 sive. Furthermore, a capillitium may be plain or ornamented. 

 In sporangia containing calcium, the capillitia are usually 

 beaded or encrusted, and sometimes thickly covered, as in the 

 genus Badhamia, with deposits of lime. The elater-like threads 

 of the Trichiacbae, which are without lime, are generally 

 marked with spiral bands, giving them a twisted, rope-like 

 appearance ; in Arcyriaceae we find expanding networks 

 decorated with minute prominences arranged discontinuously 

 along the threads of the meshes in a more or less spiral sequence. 

 On the other hand, there are several genera in which a capillitium 

 is either not present, or but imperfectly developed ; while in 

 a few species it is wholly absent, the cavity of the sporangium 

 being entirely filled with spores, and the walls quite destitute 

 of any elements of a capillitial nature. 



In regard to utility, it is commonly held that the capillitia of 

 Mycetozoa are supporting structures, or that they assist in the 

 dispersal of the spores ; but these ideas are apt to mislead. It 

 is true the sporangium walls are in many instances connected 

 with rigid capillitia, and that hygroscopic threads help to scatter 

 the spores ; but as some sporangia are without capillitia of any 

 kind, it is clear that these factors are not indispensable. A 

 sporangium needs to be fragile rather than firm, so that the 

 spores may escape ; and hygroscopic threads or expanding 

 networks cannot possibly scatter spores so effectually as wind 

 or rain, insects and birds. Indeed the surface nets of Stemonitis 

 often impede, rather than facilitate, the dispersal of spores. 



In studying Mycetozoa it must always be borne in mind 

 that a sporangium of this group is not, in any proper sense 

 of the term, a plant. It does not grow, in the ordinary botanical 

 meaning of the term. When a plasmodium matures and comes 

 to rest, its growth ceases ; and the developing sporangia into 



