MYCETOZOA MYXOMYCETES 



can also feed amoeba-fashion. Ldbyrinthula is marine, and in 

 its fructification each of the component cells forms four spores. 

 Leydenia has been found in the fluid of ascitic dropsy, associated 

 with malignant tumour. 



III. Myxomycetes. The fructification in this group is 

 not formed by the mere aggregation of the zoospores, but these 

 fuse by their cytoplasm to form a multinucleate body, the " Plas- 

 modium," which, after moving and growing (with nuclear division) 

 for some time like a great multinucleate Eeticularian, passes into 

 rest, and develops a fructification by the formation of a complex 

 outer wall ; within this the contents, after multiplication of the 

 nuclei, resolve themselves into uninucleate spores, each with its own 

 cyst-wall. The fructifications of this group are often conspicuous, 

 and resemble those of the Gasteromycetous fungi {e.g., the Puff- 

 balls), whence they were at first called Myxogastres. De Bary 

 first discovered their true nature in 1859, and ever since they 

 have been claimed by botanist and zoologist alike. 



The spore on germination liberates its contents as a minute 

 flagellate, with a single anterior lash and a contractile vacuole 

 (Fig. 30, C). It soon loses the lash, becomes amoeboid, and 

 feeds on bacteria, etc. (Fig. 30, D, E). In this state it can 

 pass into hypnocysts, from which, as from the spores, it emerges 

 as a flagellula. After a time the amoeboids, which may 

 multiply by fission, fuse on meeting, so as to form the 

 Plasmodium (Fig. 30, F). This contains numerous nuclei, 

 which multiply as it grows, and numerous contractile vacuoles. 

 When it attains full size it becomes negatively hydrotactic, 

 crawls to a dry place, and resolves itself into the fructification. 

 The external wall, and sometimes a basal support to the fruit, 

 are differentiated from the outer layer of protoplasm ; while the 

 nuclei within, after undergoing a final bipartition, concentrate 

 each around an independent portion of plasma, which again is 

 surrounded as a spore by a cyst -wall. Often the maturing 

 Plasmodium within the wall of the fruit is traversed by a network 

 of anastomosing tubes filled with liquid, the walls of which 

 become differentiated into membrane like the fruit-wall, and are 

 continuous therewith. As the fruit ripens the liquid dries, and 

 the tubes now form a network of hollow threads, the " capillitium," 

 often with external spiral ridges (Fig. 30, A, B). Tin- 

 very hygroscopic, and by their expansion and cent ran ion 



