DIFFUSE STAGE 



95 



due to the enormous increase in size of the egg cells in which they 

 are most commonly found, for in the pollen mother-cells in which 



Fig. 24. — Above, separate drawings of late pachytene in Chorthippus. 

 Diplotene separation has begun in the precocious P chromosome. 

 X shown in each figure. (R), (L), direction of relational coiling. 

 L, N, M, P, S, chromosome types. 



Below, early diplotene nucleus with three L bivalents drawn 

 separately with the numbers of total and terminal chiasmata 

 under each and the directions of chromatid coiling shown at 

 chiasmata, R"" and L''. x 2,000 (D. 1936^). 



they are also found a contraction actually occurs at this period 

 {e.g., in Mitrastemon and other plants). 



(ii) The Separation of Chromosomes and the Origin of Chiasmata. 



