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INTRODUCTION TO CYTOLOGY 



conjugation (E 2 ) and take the form of rod tetrads (F^ like those described 

 by Riickert and Haecker. While opening out in this manner the longi- 



FIG. 96. Diagram showing the origin of the tetrad of chromatids (D) according to 

 Scheme A (Ai-Ci) and Scheme B (At-Ct), and the further transformation of this tetrad into 

 tetrads of five types 



tudinal halves of each chromosome may diverge where the two chromo- 

 somes remain in contact (E 3 ), the tetrad eventually taking the form of a 

 cross (^ 3 ) as in the cases described by Paulmier and by Foot and Strobell. 



