Calotricheae. Ill 



CALOTRICHEAE. 



The varied types of ornamentation under the form of warts, 

 spines, or raised bands, often arranged in the form of half-rings, 

 or anastomosing to form a network on the surface of the capil- 

 litium tubes, constitute the most pronounced character of the 

 present order. In connection with spore dissemination, the 

 capillitium here reaches its highest development, due to the 

 elasticity of the tubes, which are never rigid with lime, and 

 in the most perfect genera are quite free from the sporangial 

 wall. The elasticity is not due to stretching, but to the sudden 

 straightening out of previously coiled-up tubes. If an immature 

 sporangium of Arcyria cinerea having the spores and capillitium 

 fully differentiated, is hardened in alcohol, a section shows the 

 tubes of the capillitium, which are combined to form a network, 

 to be much contorted, and consequently shortened so that the 

 net-like structure is not evident, the interspaces between the 

 convolutions of the tubes being filled with spores. This arrange- 

 ment of parts continues until the spores are mature, and owing 

 to the disappearance of water, form a powdery mass, when the 

 coiled-up tubes straighten out and the network becomes fully 

 expanded, resulting in an increase of ten or more times in the 

 length and breadth of the capillitium. This expansion takes 

 place suddenly, with the result that the mass of spores are 

 carried up and dispersed. During the expansion of the capil- 

 litium the sporangial wall is torn into fragments, and disappears 

 with the exception of a small portion at the base which, owing 

 to its firmer consistency and comparative freedom from the 

 expansion exerted by the capillitium, remains in the form of 

 a cup or calyculus. In the genius Trichia the free tubes or 

 elaters are very much coiled up and contorted until the spores 

 are mature, when by suddenly straightening out, the wall of 

 the sporangium is ruptured and some of the spores thrown out, 

 but the arrangement is not so perfect as in Arcyria. In some 

 of the comparatively imperfect genera, as Perickaena, the 

 capillitium is scanty or obsolete. Yellow is the predominating 



