ZYGNEMACE^E. 



233 



similar processes from parallel filaments (a, b, Fig. 156). 

 Upon meeting, the ends of the processes flatten upon each 

 other, the walls fuse together, and soon afterward become 

 absorbed, thus making a channel leading from one cell 

 to the other (Fig. 157). Through this channel the proto- 



Pio. 156. 



Fig 156. Beginning of the process of conjugation m Spirogyra longata. a, 

 beginning of the formation of lateral tubes ; b, c, the tubes in contact. X 550. 

 After Sachs. 



Fig. 157. Conjugation of Spirogyra longata. A, the protoplasm passing from 

 one cell to the other at a ; b, the mass of protoplasm formed by the union of the 

 protoplasmic contents of the two cells. 



B, two young xygospores (c), each with a cell-wall. They contain numerous oil 

 drops, and are still enclosed by the walls of the parent cell, x 550. After Sachs. 



plasm of one cell passes into the other, and the two fuse into 

 one mass, which becomes rounded, and in a short time secretes 

 a wall of cellulose around itself (Fig. 157, A and B). The 

 zygospore thus formed is set free by the decay of the dead 



