THE MYCETOZOA 



55 



meshes of which the ripe spores escape ; and in Comatricha it is 

 evanescent, and disappears soon after the sporangia are ripe. 



The capillitium also presents great variation. In the genera form- 

 ing the Calcarineae the lime may be uniformly distributed through 

 it (Badhamia, Figs. 9 and 10) or collected into lumps ("lime-knots") 

 at the points of junction of the reticulum (Physarum, Fig. 13, b, 

 Fuligo, Craterium). In Chondrioderma (Fig. 1 3, e and /), Didymium, 

 and others the lime is only laid down in or on the sporangium wall 

 and the capillitium is free from it. The strands of the capillitium 

 are generally, though not invariably, continuous at the periphery 

 with the sporangium wall, and internally with the columella, if this 

 structure is present. 



FIG. 14. 



a, four sporangia of Stemonitis splendens, Rost. ; that to the right is represented free from 

 npores and shows the columella extending nearly to the top ; x 2. 6, part of an empty 

 sporangium of S. splendens, showing the columella (c) and a branch springing from it and 

 dividing to form the surface network of the capillitium. To the right a group of spores, d, e, 

 stages in the development of the sporangia of Stemonitis ferruginea, Ehrenb., showing the 

 development of the columella in the axis of the young sporangium. The space between the 

 columella and the protoplasm is artificial. /, empty sporangium of Dictydium umbilicatum, 

 Schrad., x 30. (d and e after de Bary, 2 ; the other figures after A. Lister, 18.) 



The capillitium attains its most elaborate development in the 

 Arcyriaceae and Trichiaceae (Fig. 15). In the former it consists of 

 an elastic network, attached or not to the base of the sporangium, 

 but free from its sides, and with the strands beset with spines or 

 transverse thickenings, resembling cogs on a wheel (Fig. 1 5, /). At 

 maturity the evanescent film of the sporangium wall'gives way and 

 the capillitium expands into a long loose tangle, scattering the spores. 



In the Trichiaceae the threads of the capillitium have spiral 

 thickenings. In Hemitrichia the threads are united into a network, 

 as in Arcyria, but in Trichia they are usually unbranched and lie 

 free among the spores (Figs. 11, 12, and 15, b). Owing to their 

 spiral sculpture they twist and untwist with varying changes of 

 moisture, and thus subserve the distribution of the spores. 



In a large section of genera, the Anemineae, a capillitium is 

 absent. 



