THE PATHOGENIC SLIME-FUNGI. 523 



mode of reproduction a close resemblance to the Fungi, and as 

 a result of their lack of chlorophyll, they share with Bac- 

 teria and Fungi the peculiarities of saprophytic and parasitic 

 nutrition. 



The vegetative body of the Slime-fungi consists of naked 

 protoplasm without a firm membrane. Multiplication is effected 

 chiefly by spherical spores with the same external appearance 

 as the usual fungus-spore. Immediately on reaching maturity 

 the spores germinate in water and burst, setting free a mass of 

 plasma provided with a nucleus and vacuoles, and in which an 

 outer movable hyaloplasma can be distinguished from an enclosed 

 granular plasma. The hyaloplasma gives off delicate pseudopodia 

 capable of extension and retraction, it may also take the form 

 of a flagellum or of cilia. The organism is enabled by means 

 of the pseudopodia to creep over firm objects as an " amoeba '' ; 

 by the cilia it can propel itself through water, as a " swarmer " 

 or " zoospore." A zoospore in the course of its development 

 generally loses its cilia and becomes an amoeba, and both 

 forms can multiply by division. The amoebae creep together 

 in large numbers, and either coalesce completely into masses, 

 or remain simply in contact as aggregations. In this way 

 Plasmodia are formed, frequently of considerable size and ' of 

 conspicuous colour. The plasmodia maintain a constant move- 

 ment, both as a whole and in the form of internal streamings. 

 Eesting stages have been observed at each motile stage of 

 the life-history; thus swarm-spores rest as microcysts, young 

 Plasmodia as thick-walled cysts, and mature plasmodia as multi- 

 cellular sclerotia. 



Multiplication of the Myxomycetes also takes place by spore- 

 formation. In the Acrasieae and Phytomyxinae the spores are 

 developed freely from the plasma. The Exosporeae, a very 

 small division, have their spores developed on the outside 

 of sporophores. In the greater number (Endosporeae) the 

 spores are formed in special enclosures, which may be a spor- 

 angium produced from a single plasmodium, or an aethalium — a 

 cushion-like structure consisting of numerous imperfectly defined 

 sporangia. The sporangia are often of considerable size, some- 

 times not unlike the sporocarps of the Gasteromycetes, spherical 

 or pear-shaped and stalked. Sporangia of this highly developed 

 kind may even exhibit a certain differentiation into a wall or 



