280 Cardiff: Synapsis and reduction 



moieties often remain separated for a short distance at their ends 

 and by this means these investigators believe they can follow the 

 history of the thread through the prophases of the heterotypic 

 division. The chromosomes of the prophase assume ring- and 

 cross-forms similar to many of the others recently figured for animals 

 and give appearances that would indicate that the first division is 

 transverse. Schreiner and Schreiner, however, are confident that 

 both divisions are longitudinal, the heterotypic taking place along 

 the line of original fusion of the prereduction chromosomes. 



Thus there are, evidently, two schools of the more recent in- 

 vestigators which seem to differ radically in regard to the details 

 of reduction, though they are in agreement on one essential point ; 

 namely, that the first division is heterotypic and separates whole 

 somatic chromosomes which had retained their individuality 

 through the growth period of the organism. 



The present work was taken up with the hope of throwing 

 some light upon the phenomenon of synapsis and its relation to 

 reduction division. A number of forms have been examined. The 

 results of observations upon four of the forms are presented here. 

 Results from other forms will follow in a succeeding paper. Ob- 

 servations were made upon sporogenous tissue in all stages from 

 early archesporium to spore formation, but chief attention was 

 given to synaptic and presynaptic stages. 



The forms chosen represent four groups : namely, pterido- 

 phytes, gymnosperms, monocotyledons, and dicotyledons. As 

 the results agree in the essential points, they seem to indicate that 

 the reduction process is the same throughout the plant kingdom. 



No pretense is made of citing all the literature on reduction, 

 nor of going into a detailed discussion of the philosophical aspects 

 of the question. Both of these points have been admirably taken 

 up recently by Allen ('050), Davis ('05), Gregoire ('05), and sev- 

 eral others. 



The material for this work was collected in the vicinity of New 

 York City in the spring of 1905, except in the case of Botryclnuni, 

 which was collected in Indiana and Ohio the year previous. The 

 ordinary methods of microtechnique were used in making the 

 preparations for study. Many preparations were made of each 

 type examined. 



