SI-XT. I 



CRYPTOGAMS 



341 



extremities of short stalks, 

 in the Myxomycetes. 



SKXTAL UKI-KODUCTION is entirely absent 



A good example of the development of the plasmodia from the spores is afforded 

 ly Chondrioderma '////;-/////, a Slime-Fungus, common on decaying leaves, dung, 

 etc., upon which it forms small, round, sessile sporangia. The germination of the 

 -pores (Fig. 59 a) may be easily observed when cultivated in an infusion of 

 (.'abhage leaves or other vegetable matter. The spore-wall is ruptured and left 

 empty by the escaping protoplast. After developing a flagellum or riLU'M as an 

 organ of motion, the protoplast swims about in the water, being converted into 

 a sw.viiM-.si'OUK (Fig. 59 e-g), with a cell-nucleus in its anterior or ciliated end, 

 and a contractile vacuole in the 

 posterior end of its body. Eventu- 

 ally the cilium is drawn in, and the 

 swarm - spore becomes transformed 

 into a MYXAMOKiiA ; these have the 

 i-apacity of multiplication by division. 

 In conditions unfavourable for their 

 development they surround them- 

 selves with ,i wall, and as MITKIM Y.vrs 

 pass into a state of rest from which. 

 under favourable conditions, they 

 again emerge as swarm - spores. 

 Ultimately a number of the myx- 

 amoebae approach close together (Fig. 

 59 I) and coalesce, forming small 

 plasmodia (Fig. 59 m), which in turn 

 fuse with others into larger plasmodia 

 (Fig. 59 n) ; no nuclear fusion accompanies this coalescence. Both the amoebae and 

 plasmodia are nourished by the small food particles taken up by the protoplasm, 

 which also exhibits active, internal, streaming movements. After an interval of 

 a few days the plasmodium creeps to the surface of the substratum, and passing 

 into a resting stage becomes at length converted into a white sporangium with a 

 double wall, consisting of an outer, calcareous, brittle peridium and an inner 

 and thinner enveloping pellicle which, in addition to the numerous spores, encloses 

 also a poorly developed capillitinm. 



The development of the other Myxomycetes is -accomplished in a similar 

 manm-r. Very large plasmodia, often over a foot in breadth, of a bright yellow 

 colour and creamy consistency, are formed by Fuliyo rarians (Aethnfinnt wjiticum), 

 and as the "flowers of tan " are often found in summer on moist tan bark. 

 If exposed to desiccation, the plasmodia of this Myxomycete pass into a 

 resting state, and become converted into spherical or strand-like SCLEIKITIA, 

 from which a plasmodium is again produced on a further supply of water. 

 Filially, the whole plasmodium becomes transformed into a dry cushion or 

 cake-shaped fructification of a white, yellowish, or .brown colour. The fructi- 

 fication, in this instance, is enveloped by an outer calcareous crust or rind, and 

 is subdivided by numerous internal septa. It encloses numerous dark violet- 

 coloured spores, and is traversed by a filamentous capillitium, in which are 

 dispersed irregularly-shaped vesicles containing granules of calcium carbonate. 

 A fructification of this nature, or so-called fethalium, consists, therefore, of a 

 number of sporangia combined together, while iu most of the Myxomycetes the 



Kio. 265. Ri)' t'ructilications, after i listharj:c of tho 

 spores. -I. Sti'tnonitit fusctt (x 10); 7,', An-i/rin 

 <w (x I'-') : '', Ci-ibrarin rufc (x 32). 



