SPIROGYRA SP. 113 



4. Can you detect any difference between the cells, 

 physiologically? From your own observations do 

 you think there is any correlation between the struc- 

 ture of cells and their function? Explain clearly. 



5. Is there any evidence in Spirogyra of a correlation 

 between structure and environment? Explain. 



D. Asexual Reproduction in Spirogyra: 



i. From what you have already learned of Spirogyra, 

 state the possibilites of vegetative propagation in 

 this plant. 



E. Sexual Reproduction in Spirogyra: 



1. Use fresh material, if possible; otherwise preserved 

 specimens, or prepared slides. 



2. Observe the various stages in the fusion of two cells 

 (gametes). Do the fusing gametes belong to the 

 same, or to different filaments? Observe the 

 conjugation-tubes connecting adjacent filaments. 1 

 What is their function? Their relative diameter? 

 Try to find tubes in various stages of formation. 

 Are their distal ends open before they come into 

 contact ? How is the opening made ? Do the tubes 

 grow together or merely touch each other? 



3. Does conjugation seem to be a function of all the 

 cells of the filament, or of certain cells only? 



4. Do the gametes pass from either filament to the 

 other, or do the cells of a given filament all behave 

 alike in this respect? In this connection see 

 whether all the zygospores occur in one filament, 

 or not. 



ir The form of conjugation described in the outline above, is termed 

 "scalariform" (ladder-like). Another type, known as "lateral" con- 

 jugation may frequently be met with, in which the gametes are formed by 

 adjacent cells of the same filament. In less frequent cases the protoplast 

 of a single cell organizes itself into a reproductive body (aplanospore) 

 without conjugation. This process is a type of parthenogenesis. 



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