DEVELOPMENT OF PLANTS 151 



frequently greatly elongated. It is bounded by a wall and within 

 is the living substance or protoplasm. The more important parts 

 of the living substance are a viscid rather watery material termed 

 the cytoplasm and a minute denser body, the nucleus, which is 

 immersed in the cytoplasm. A spore is a special kind of cell 



FIG. 89. 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. 



that is capable of germinating under favorable conditions and 

 producing a plant. In this case it is advisable when germinating 

 the spores to place them in a nutrient solution made by boiling 

 in water bits of wood upon which the sporangia were growing. 

 Germination will begin in about one day. As the spore wall 

 ruptures the contents escapes as a naked bit of protoplasm 

 (Fig. 89, B) which possesses a singular power of motion. This 

 motility is due either to the slow creeping or streaming motion 



