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GENERAL BIOLOGY 









FIG. 56. Conjugation of two strands of Spirogyra. The upper cells 

 are just forming the conjugating tube. This has been established in tin- 

 next couple of cells. In the next two pairs of cells the cell-protoplasm is 

 passing over from one strand to the other. In the lowermost cell this 

 process has been completed, and the cell-contents have fused into a 

 zygote, which secretes a thick wall about itself and becomes a resting 

 spore. 



FIG. 57. Conjugation of Mougeotia. In this form the cell-contents 

 fuse midway between the two conjugating strands. 



The difference between the gametes may be of 

 varying degrees. In Spirogyra, in which the long 



