DEVELOPMENT OF PLANTS 



145 



moist dish in a complex skein-like mass or if a glass slide, down 

 which water is slowly allowed to trickle, is brought in contact 

 with the Plasmodium it may be observed creeping up the slide 

 toward the source of the water supply. The slime moulds do 

 not contain chlorophyll and are therefore dependent upon or- 

 ganic food. Plants that feed in this way are called saprophytes. 

 Since the plasmodium is not surrounded by a cell wall feeding 

 becomes a simple matter. The jelly-like mass engulfs the decay- 



FlG. 



Fig. 90. 



Fig. 89. Mobile phase in life of slime mould: A, group of spores. B, 

 germination of a spore. C, two forms of zoospores greatly enlarged. The 

 right-hand one mobile owing to a streaming movement of its protoplasm 

 and the left-hand one moves about owing to the rapid movements of the 

 cilium, c. D, association of the zoospores preliminary to the formation of 

 a Plasmodium. E, Plasmodium. The arrow indicates the direction of the 

 streaming movement. 



Fig. 90. Character of the capillitium: A, in Arcyria. B, in Trichia, por- 

 tion of thread enlarged on the left hand. 



ing particles or other foods and after digesting the nourishing 

 portions casts out the worthless part. As the plasmodium ap- 

 proaches the final stage of its life, its nature appears to change 

 completely for now it avoids moisture and seeks the light. It 

 creeps to the surface of the wood or leaves in which it has been 



