J. SLADE ON MYCETOZOA. 435 



As before mentioned, these sporangia are the only conspicuous 

 stage in the life-history of these organisms : they appear as 

 minute objects, as small as mustard seeds, or as black, hair-like, 

 minute stalks on dead sticks, rotten wood, decaying leaves in 

 damp places. 



When a spore falls on a damp surface, or in water, it germi- 

 nates. Out of the thick-walled spore comes a swarm spore, which 

 is locomotive, either by means of a single cilium, as a flagellate 

 infusorium, or by means of pseudopodia, as an anioeba. A 

 number of spores germinating together may coalesce to form 

 a plasmodium, each individual in the community preserving its 

 own nucleus, which may divide and increase in the usual way. 

 They may even separate, and after a time reunite. 



The formation of a plasmodium is highly characteristic of the 

 Mycetozoa, and does not occur elsewhere. Plasmodia for the 

 most part are inconspicuous bodies. They live usually in the 

 interior of rotten parts of plants, especially rotten wood, 

 and are not visible to the naked eye till they come to the surface 

 to form sporangia. 



The brilliant and pure colours of plasmodia are remarkable : 

 as white, rose red, orange yellow, lemon yellow, purple, sap green. 

 They move about in search of food, may be cultivated, grown 

 on glass slips for microscopic observation, and have been seen 

 devouring bacteria most voraciously. 



In Fuligo varians, or Flower of Tan, a number of plasmodia 

 fuse together into a narrow reticulum, w T hich swells into a 

 cushion-shaped mass, sometimes 12 inches in diameter, full of lime 

 salts, which, with the colouring-matter, forms a crust when dry. 



In Badhamia the plasmodium thrives on the inner bark of 

 felled elms, and is difficult to find, as it mostly incloses broken 

 fragments of the bark. But before fruiting, these fragments are 

 rejected, and it becomes pure white. 



The plasmodium of Stemonites may be found emerging from 

 the sawn surface of fir stumps, covering an area of 6 or 7 square 

 inches. 



In unfavourable conditions a plasmodium may become en- 

 cysted, forming a transitory resting stage ; and even after the 

 lapse of several months, if placed in water, it revives, escapes 

 from its cyst, and continues to live as before. 



Ultimately the plasmodium rests, ceases to feed, concentrates, 



