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SIXTH SUBDIVISIOX. 

 MYCETOZOA. 



The Mycetozoa are a group of organisms separated by a great gulf 

 from the Thallophytes, but presenting certain points of resemblance to 

 the Fungi which may here be indicated, while the amount of that resem- 

 blance and the degree of their divergence will be more fittingly esti-- 

 mated at the end of this chapter. Their nutrition is saprophytic, and the 

 organs of reproduction are sufficiently like those of the Fungi to justify 

 the use of the terms sporange, spore^ swarm-spore. The vegetative body, 

 on the other hand, differs in structure tofo ccelo from any form of thallus. 

 It consists of a naked protoplasmic body, either a plasmode formed by 

 the coalescence of peculiar swarm-spores, or an aggregation of such 

 swarm-spores. The first case is characteristic of one class, the Myxo- 

 mycetes ; the second case of the other smaller class, the Acrasiea^. 



Class XXIII. — Myxomycetes. 



The ripe spores of ^lyxomycetes are capable of germination at once, 

 and many of them retain this power for considerable periods, some for 

 as long as several years. Most germinate at the ordinary spring 

 or summer temperature, and in pure water, while others require a 

 nutrient solution. The germination of the spores of Cribrarieae and 

 Tubulinae has not been observed, and the failure of the attempts to pro- 

 cure it may be owing either to the supply of unsuitable media or to a 

 necessity for a period of rest — more likely the former. In structure 

 the spores resemble those of fungi, as has been said. The wall 

 is either smooth or sculptured on the outer surface, and the protoplasm 

 contains one, sometimes two, nuclei. The act of germination consists of 

 the emission of a swarm-spore. The membrane opens and the proto- 

 plasm escapes with a creeping motion. This naked protoplasmic bodv 

 or swarm-spore then exhibits amoeboid movements, protruding and with- 

 drawing irregular processes, becoming more or less elongated, and 



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