6 



MYCETOZOA 



spores, often of irregular shape and containing several nuclei, 

 are of frequent occurrence. 



The spores while remaining in a dry state retain their 

 vitality for several years. The length of time that elapses 

 before the germination of the spore after it has been placed 

 in water varies with the species, and often in different gather- 

 ings of the same species. Observations on the darker spores of 

 Stemonitis fusca showed germination after nine or twelve hours, 

 while in the pale-spored variety it occurred in twenty-eight 

 minutes. In Reticularia Lycoperdon it usually takes place 

 in less than an hour in fresh gatherings ; spores from a speci- 

 men which had been stored for nearly three years began to 

 germinate in four hours, and in twenty hours the contents 



of nearly every spore had 

 emerged. The spores of 

 Didymium difforme that had 

 been preserved three years 

 and nine months, on being 

 placed in water produced 

 abundant swarm - cells in 

 twenty-eight hours, and in 

 a few days all the spores 

 appeared to have germinated. 

 The spore-wall is ruptured 

 by the swelling of the con- 

 tents, which slowly emerge 

 and lie as a nearly pellucid 

 globule by the side of the 

 empty spore - case.* After 

 remaining quiescent for a 

 few minutes amoeboid move- 



Fig. 1. — Didymium difforme Duby. 



a. Spore. 



b. Swarm-cell escaping from the spore-case. 



c. Newly hatched swarm-cell containing a 

 nucleus and three vacuoles. 



rf. Flagellated swarm-cell. 



e. Swarm-cell, with two vacuoles containing mentS begin tO take place, 

 bacteria, and produced at the posterior QT -,rl olinvflir aft-Q-rw-nrrlQ a 

 end into pseudopodia, to one of which * na snomv altera aras a 

 a bacterium is attached. flagellum is produced. IlllS 



/. Amoeboid swarm-cell. . °, n , , , j .. 



Magnified 720 times. is at first a somewhat tenta- 



tive process, and the flagellum 

 is frequently withdrawn ; but within a quarter of an hour 

 it acquires its full length of about 15 /x, and by its lashing 

 strokes the swarm-cell swims off with a dancing movement. 

 At this stage it is pyriform in shape, the interior body- 

 substance is granular and contains a contractile vacuole, 

 and often one or more vacuoles in addition which do not 

 usually show contraction. At the narrow end is placed the 

 nucleus, which can easily be recognised by its lighter and 

 more homogeneous appearance and central nucleolus. The 



* Pinoy has shown that in the case of the Sorophora the presence of certain bacteria 

 is necessary for the germination of the spores, and his experiments suggest that this 

 may also be true of the Mycetozoa (Ann. Inst. Pasteur, xx. 627 & 688). 



