No. 463.) STUDIES ON PLANT CELL.— VI. 483 
of an accumulation of granular material in the nucleus of the 
central cell of Picea and other cases might be cited which super- 
ficially resemble synapsis but have no fundamental relation to 
this peculiar nuclear activity. 
Evidence is steadily accumulating that synapsis is a very 
important period of sporogenesis. Some authors hold, as will 
be described presently, that it is the time when paternal and 
maternal chromosomes, which have remained separate through- 
out the sporophyte generation, become associated in pairs to 
give the reduced number of the gametophyte. This conclusion 
makes synapsis the actual period of chromosome reduction and 
the two succeeding mitoses become merely distributing divisions 
of the newly formed chromosomes. Montgomery (: 01) first 
suggested for animals that synapsis involved a union of maternal 
and paternal chromosomes in pairs. Other views, however, 
regard the reduction of the chromosomes as merely the tempo- 
rary union of paternal and maternal elements, end to end, to 
form a bivalent chromosome characteristic of the first or hetero- 
typic mitosis. According to this view the bivalent chromosomes 
divide transversely so that the halves are distributed as whole 
chromosomes in the first mitosis. 
Two very important papers on reduction phenomena have 
appeared this year (1905) both of which were preceded by pre- 
liminary publications, that of Farmer and Moore (:03) and 
Allen (:04). These two accounts best represent the attitude of 
the opposing schools and will be made the chief texts of our 
treatment. The fundamental points of difference concern the 
events of synapsis and the heterotypic mitosis while there is 
complete agreement in the general interpretation of the homo- 
typic mitosis. All authors have reached essentially the same 
conclusions as regards the purpose and final results of the 
reduction divisions but the details of the processes of synapsis and 
the prophase of the heterotypic mitosis are described in radically 
different ways by various investigators. However, as has been 
stated, the views fall into two groups Or schools, one led by 
Farmer and Moore with whom Strasburger’s recent paper, 
“Ueber Reduktionsteilung " (:04) expresses essential agree- 
ment. The other school includes Allen, Rosenberg, and the 
