MYXOMYCETES. 



[ 530 ] 



MYXOMYCETES. 



of some peridia, calcareous crj-stalloids are 

 found. Tlie mode of dehiscence varies. 

 fSonietimes an irregular opening is formed 

 at tlie summit, as iu Physarum ; sometimes 

 tlie peridium opens like a little box, as in 

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

 upper half falls oiF, leaving a cup-shaped 

 base, as in Arcyria ; or the membrane may 

 be very delicate, and break up entirely into 

 little scales, which fall oiF and leave the 

 capxlUtium with its spores naked, as in Ste- 

 monitis. The capillitium or sporiferous 

 structiu-e is formed of filaments, simple or 

 branched, free and loose, or anastomosing 

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

 iu Trichia these have spiral markings, and 

 resemble the elaters of Hepaticne (PI. 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, columeUa or 

 styJidium, in the centre of the capillitium. 

 The spores appear to be produced upon 

 these filaments by grooving 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. 



In 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 partiiJ views. 



Synopsis of British Genera, 



* Teichiacei. Primary mucilage con- 

 joining several distinct peridia. Filaments 

 of tlie capillitium free, entwined, elastic, or 

 almost absent. 



Licea. Peridium subpersistent, mem- 

 branous, bmsting irregularly. Spores in 

 heaps, with scarcely any filaments. 



Pericha'tia. Peridium persistent, mem- 

 branous, bursting by a circumscissile slit. 

 Fila iients few, free. 



Trichia. Peridium simple, persistent, 

 bursting irregularly at the summit. Eila- 

 ments densely interwoven, elastic. 



Arcyria. Peridium simple, membranous, 

 splitting all round at the base, the upper 



part very fugacious. Filaments densely in- 

 terwoven, elastic. 



** Stemomtf-i. Primary mucilage con- 

 necting several distinct ]jeridia. Filaments 

 conjoined into a network, adnate or innate. 



Cribraria. Peridium simple, membra- 

 nous, the upper part falling olf. FUamenta 

 adherent in the interior, at length exjiand- 

 ing into a free network above. 



Dictydium. Peridium simple, subglo- 

 bose ; very delicately membranous, bursting 

 indeterminately, leaving the filaments (in- 

 nate) forming a cage-like latticed capUli- 

 tium. 



Stemonitis. Peridium simple, globose or 

 cylindi-ical, delicately membranous, finally 

 evanescent. Filaments forming a determi- 

 nate capillitium, attached to a bristle-hke 

 central columella, and forming a network 

 around it. 



Diachfcu. Peridium simple, ovate-oblong, 

 membranous, detached in fragments, leaving' 

 a radiately reticulate capillitium, with a 

 floccose gi'umous pulverident axis. 



Enerthoiema. Peridium simple, globose, 

 membranous, at length evanescent, laying 

 bare a conical columella with a cup at 

 the summit, bearing beneath ascending en- 

 twined filanients. 



*** Physabei. Primary mucilage spread- 

 ing widely, passing into many peridia. Fila- 

 ments adnate, strnight, vague. Spores black. 



Craterium. Peridium simple, varied, 

 papery, persistent, closed b}* a Hd, which 

 finally falls ofi". Capillitium somewhat 

 chambered, foi-mcd of crowded filaments, 

 at length erect. 



Physarum. Peridium simple, variable, 

 naked, membranous, bm-sting irregularly. 

 Capillitium floccose; filaments at first joined 

 into a net or forked. 



Didymiiim. Peridium double ; the outer 

 bark-like, breaking up into little furfura- 

 ceous scales or mealy down, the irmer mem- 

 branous, bursting irregularly; filaments 

 vague, adnate to the peridium. 



Uidcrma. Peridium double ; outer crust- 

 like, distinct, brittle, dehiscent, the inner 

 very delicately membranous, evanescent ; 

 filaments vague, adnate to the base. 



**** ^TH ALINE I. Primaiy mucilage 

 producing one peridium. 



Spumaria. Peridium indeterminate, 

 crustaceous, divided into cells by regidar 

 ascending folds, and finally falling awa3\ 

 No inlernal filanients. 



Aifh(dium. Peridium indeterminate, fra- 



gile, falling 



away, 



covered with a floccose 



