HIDDEN MARRIAGES 



569 



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Fio. 718. Trichia varia. 



Common on decaying wood. The densely packed sporangia of ochreous tint are she 



IE. Step. 



slightly enlarged. 



out a whip-like process on the advancing side, surrounding Bacteria and 

 other minute organisms and feeding upon them, chiefly in decaying wood 

 and other vegetable matter. At a certain period of their life many of 

 these come together and unite into a plasmodium, a creamy mass of naked 

 protoplasm, which afterwards divides and forms sporangia, enclosing 

 numerous dust-like spores like those by which the swarm-cells were 

 originally produced. These sporangia differ greatly in form and size, each 

 genus having its characteristic form and the species differing from each 

 other in minor points, some becoming combined in cake-like or cushion- 

 like masses of relatively large size, others forming small spherical or 

 cylindrical bodies, stalked or sessile. 



Each swarm-cell possesses a single nucleus and a contractile vacuole. 

 From the rear end it puts out finger-like processes (pseudopodia) with which 

 it catches its food. The pseudopodia draw it into the body, where it is 

 digested in the vacuoles. The swarm-cells increase in numbers by each 

 dividing into two, and these dividing in the same manner again and again. 

 When they unite into the creamy mass known as the plasmodium, they 

 alternately advance and recede as a whole, but the movement is always 

 more in one direction than the other. After a few hours the plasmodium 



