MYXOMYCETES. 



[ 530 ] 



MYXOMYCETES. 



of some peridia, calcareous crystalloids are 

 found. The mode of deliiscence varies. 

 Sometimes an irregular opening is formed 

 at the summit, as in Physarum ; sometimes 

 the peridium opens like a little box, as in 

 Craterium (fig. 145, p. 213) ; sometimes the 

 upper half falls off, leaving a cup-shaped 

 base, as in Arcyria ; or the membrane may 

 be very delicate, and break up entirely into 

 little scales, which fall off and leave the 

 capillitium with its spores naked, as in Ste- 

 monitis. The capillitium or sporiferous 

 structure is formed of filaments, simple or 

 branched, free and loose, or anastomosing 

 so as to form a network (fig. 147, p. 214) ; 

 in Trichia these have spiral markings, and 

 resemble the elaters of Hepaticse (PL 40. 

 fig. 39). The filaments are often elastic, 

 and when the peridium bursts they rise 

 from the bottom of it, forming a coloured, 

 erect or drooping plume (Arcyria). In 

 many species there is a stalk, columella or 

 stylidium, in the centre of the capillitium. 

 The spores appear to be produced upon 

 these filaments by growing out from them 

 in the manner of basidiospores. They are 

 formed in vast numbers, and lie, when com- 

 plete, on the branches and in the interstices 

 of the capillitium. 



Ju germination, each spore liberates its 

 entire protoplasm, which exhibits amoeboid 

 movements, and protrudes pseudopodia, 

 which anastomose as in Gromia. In some 

 instances, these amoeboid bodies acquire 

 cilia, resembling Monads. They then con- 

 jugate, finally forming a sporangium, in 

 which the capillitium with its very nume- 

 rous spores are produced. Some authors 

 regard these organisms as animal, but this 

 opinion seems to rest upon partial views. 



Synopsis of British Genera. 



* TBICHIACEI. Primary mucilage con- 

 joining several distinct peridia. Filaments 

 of the capillitium free, entwined, elastic, or 

 almost absent. 



Licea. Peridium subpersistent, mem- 

 branous, bursting irregularly. Spores in 

 heaps, with scarcely any filaments. 



Perichcena. Peridium persistent, mem- 

 branous, bursting by a circumscissile slit. 

 Filaments few, free. 



Trichia. Peridium simple, persistent, 

 bursting irregularly at the summit. Fila- 

 ments densely interwoven, elastic. 



Arcyria. Peridium simple, membranous, 

 splitting all round at the base, the upper 



part very fugacious. Filaments densely in- 

 terwoven, elastic. 



* STEMONITEI. Primary mucilage con- 

 necting several distinct peridia. Filaments 

 conjoined into a network, adnate or innate. 



Cribraria. Peridium simple, membra- 

 nous, the upper part falling off. Filaments 

 adherent in the interior, at length expand- 

 ing into a free network above. 



Dictydium. Peridium simple, subglo- 

 bose ; very delicately membranous, bur>lin^ 

 indeterminately, leaving the filaments (in- 

 nate) forming " a cage-like latticed capilli- 

 tium. 



Stemonitis. Peridium simple, globose or 

 cylindrical, delicately membranous, finally 

 evanescent. Filaments forming a determi- 

 nate capillitium, attached to a bristle-like 

 central columella, and forming a network 

 around it. 



Diacheea. Peridium simple, ovate-oblong, 

 membranous, detached in fragments, leaving 

 a radiately reticulate capillitium, with a 

 floccose grumous pulverulent axis. 



Enertlienema. Peridium simple, globose, 

 membranous, at length evanescent, laying 

 bare a conical columella with a cup at 

 the summit, bearing beneath ascending en- 

 twined filaments. 



'* PHYSABEI. Primary mucilage spread- 

 ing widely, passing into many peridia. Fila- 

 ments adnate, straight, vague. Spores black. 



Craterium. Peridium simple, varied, 

 papery, persistent, closed by a lid, which 

 finally falls off. Capillitium somewhat 

 chambered, formed of crowded filaments, 

 at length erect. 



Physarum. Peridium simple, variable, 

 naked, membranous, bursting irregularly. 

 Capillitium floccose; filaments at first joined 

 into a net or forked. 



Didymium. Peridium double ; the outer 

 bark-like, breaking up into little furfura- 

 ceous scales or mealy down, the inner mem- 

 branous, bursting irregularly ; filaments 

 vague, adnate to the peridium. 



Diderma. Peridium double ; outer crust- 

 like, distinct, brittle, dehiscent, the inner 

 very delicately membranous, evanescent ; 

 filaments vague, adnate to the base. 



**** ^ETHALINEI. Primary mucilage 

 producing one peridium. 



Spumaria. Peridium indeterminate, 

 crustaceous, divided into cells by regular 

 ascending folds, and finally falling away. 

 No internal filaments. 



_ jEthalium. Peridium indeterminate, fra- 

 gile, falling away, covered with a floccose 



