542 The Ohio Naturalist. ' [Vol. IX, No. 8, 



SUMMARY. 



1. The chromatin network of the resting nucleus is trans- 

 formed into a continuous spirem with no definite evidence of the 

 presence of protochromosomes. 



2. No spliting or doubling of the linin thread or of the 

 chromatin granules was observed; the chromosomes are appar- 

 .ently arranged end to end in the spirem. 



3. Synizesis appeared at various stages but was apparently 

 -not constant for any particular stage. 



4. The continuous spirem shortens and twists into 8 loops, 

 radiating outward toward the nuclear wall, the crossing threads 

 forming a central knot. 



5. The 8 loops break apart at the center to form the 8 

 ;bivalent chromosomes. 



6. Fine connecting strands often appear between the 

 .chromosomes and the nuclear wall or between the chromosomes 

 themselves. 



7. The chromosomes show a striking difference as to shape 

 and size. 



8. The pair of univalent chromosomes, which must have 

 ■united to form a bivalent chromosome are alike in shape and 

 ;Size and apparently represent maternal and paternal bodies. 



LITERATURE. 



Brown, W. H. The Nature of the Embrvo-Sac of Peper- 

 ,omia. Bot, Gaz. 46:445-460, 1908. 



Gates, R. R. A Studv of Reduction in Oenothera rubri- 

 nervis. Bot.' Gaz. 46:1-34,' 1908. 



ScHAFFNER, J. H. The Division of the Macrospore Nucleus. 

 :Bot. Gaz. 23:430-452. 1897. 



^-^The Reduction Division in the Microsporocytes of 



>gave virginica. Bot. Gaz. 47:198-214. 1909. 



EXPLANATION OF PLATE XXXII. 



Fig. 1. Mother cell of microsporocytes. 



Fig. 2. The same. 



Fig. 3. Microsporocyte with chromatin network and showing irregular 



masses. 

 Fig. 4. Microsporocyte with delicate linin threads and prominent 



chromatin granules. 

 Fig. 5. Microsporocyte with expanding nucleus and more prominent 



threads. 

 Fig. 5a. Single threads showing rows of chromatin granules. 

 Fig. (■). Threads of network adjusting themselves into a definite spirem. 

 Fig. 7. Sjjirem becoming thicker. 

 Fig. 8. Synizesis stage; massing of chromatin. 

 Fig. 9. Spirem showing irregular twisting. 

 Fig. 9a. Single threads of saine stage. 

 Fig. 10. Spirem beginning to be thrown into definite loops, the threads 



crossing a;id njiassing in the center. 



