THE MYXOMYCETES 281 



are produced. The spores on germination give rise to 

 swarm-cells, which unite together to build up the great 

 protoplasmic body with which we started. Such are 

 the rough outlines of a Myxomycete's career. We will 

 now proceed to study a particular example more in detail. 



TYPE XXVI. BADHAMIA UTRICULARIS 

 1. THE PLASMODIUM 



This Myxomycete is common in some years, though 

 rare in others: it occurs on the bark or wood of fallen 

 trees, on old garden seats, and in fact in all places 

 where timber is left exposed to damp and decay. In 

 its ordinary state the organism forms irregular flat 

 gelatinous masses of a deep chrome-yellow colour, 

 spreading and creeping over the surface of the rotting 

 wood, especially in damp weather. These creeping 

 masses are called plasmodia. A small plasmodium is 

 shown in Fig. 112. This specimen was only about half 

 an inch across, but much greater dimensions are usually 

 attained, the area covered by one plasmodium sometimes 

 amounting to as much as six square inches. The plas- 

 modium is not uniform in thickness throughout, but is 

 traversed by thicker veins, which unite together to form 

 a kind of network. The thinner protoplasmic layer 

 between the veins is sometimes interrupted so as to leave 

 some of the meshes empty. The whole plasmodium is 

 a mass of living protoplasm which is in constant move- 

 ment. The movement is of two kinds (1) an advancing 

 locomotion of the whole plasmodium, and (2) an internal 

 circulation of the protoplasm, especially in the veins. 

 The locomotion is a slow, creeping movement; the 



