284 Structural and Physiological Botany. 
comes to rest from unfavourable external conditions, or their growth 
has ceased on the formation of fruit, that the protoplasm breaks’ up 
into small cells provided with a cell-wall, but not forming a true 
tissue. Theylive on decaying and putrefying vegetable substances. 
In its membraneless condition the protoplasm displays an extraordinary 
motility ; and then, independently of the currents in its interior, the — 
whole mass creeps over or in its substratum like an animal. But when it 
passes over into the fructifying state, it breaks up into large receptacles 
or sporangia, filled with small spores, usually accompanied by a reticu- 
lation of thin-walled tubes opening into one another, a hair-like weft 
termed a cafillitium. ‘The germiaating spore, now provided with a 
cell-wall, allows the whole of its protoplasmic contents to escape in the 
form of a naked mass which assumes an elongated pointed shape, and 
acquires a cilium at one end, and thus becomes transformed into a 
swarmspore, which either takes on a rotating motion, or, changing its 
form, creeps about in an animal-like fashion like an Amceba. These 
swarming bodies multiply by division during two or three days ; and 
then a new process begins, two or more coalescing into a homogeneous 
mass of protoplasm or Alasmodium, which also moves about in an 
amoeboid manner. The plasmodium often creeps about for the space 
of a foot, the motion being caused by the projection at its margin of 
arm-like protuberances, which increase in size by fresh masses of pro- 
toplasm flowing into them. When this takes place for some time in 
one direction, the whole plasmodium has in this way shifted its place. 
These processes usually occupy a few hours; in the so-called ‘ flowers 
of tan,’ “thalium septicum, one or two hours is sufficient for the still 
motile plasmodium to become changed into the fertile discs. When 
the vital conditions are unfavourable, the swarming bodies and the 
young plasmodia become surrounded by a membrane, or encysted, like 
the infusorial animalcules, and, if kept dry, remain in this condition for 
months without losing their power of life ; when placed in water they 
recur to the motile condition. Mature ilasmiedis pass into the resting 
state when the amount of moisture or the temperature is low, forming 
a sieve-like plate or irregular tuberous body (sclerotium), and finally 
break up into a large number of round or polyhedral cells of a diameter 
of 0°025 to 0':033mm., and of a waxy or brittle texture. When placed 
in water the cell-walls which had been formed are again absorbed, and 
the plasmodia re-assume their motile condition. 
