1909] SCHAFFNER— REDUCTION DIVISION IN AGAVE 209 



Paulmier in 1899 showed that in the spermatogenesis of Anasa 

 Iristis the first division is the reduction division, and more recently 

 Montgomery, in a series of important investigations, has come to the 

 same conclusion. Griggs found a reducing division in Ascaris, and 

 observed that the chromosomes are not entirely separated until they 

 are drawn into the equatorial plane. 



Mother after a long-continued study of Podophyllum, Lilium 

 Martagon, and other plants, has come to conclusions for the most part 

 similar to the writer's, although for many years he held opposite 

 news. 



Gates, in a recent article, finds that in the reduction nucleus of 

 the microsporocytes of Oenothera rubrinervis the spirem segments 

 transversely into the 2X or sporophyte number, and that the members 

 of a pair are thus at first arranged end to end on a single thread. 

 Later the univalent chromosomes are separated, usually in pairs. 



It is needless to review the extensive recent literature of reduction, 

 for in many cases the results appear radically different from those 

 presented in this report, and in examining the drawings and conclu- 

 sions based on them there seems little possibility of harmonizing or 

 explaining the differences. 



Finally, it may be said that if any individuality whatever is ascribed 

 to the chromosomes, it becomes evident that they should be arranged 

 «"* to end to form the spirem, since this is the method in somatic 

 divisions. It i s not probable that the cell would develop a funda- 

 mentally new method of division in reduction, but rather that such 

 %ht changes would be developed in the process as would suffice to 

 brm g ab °ut the separation of the two sets of chromosomes. The 

 Process described in this paper appears to the writer to be the only 

 Possible explanation of the figures. As has been stated, however, by 

 ma king suitable selections, one could represent almost any of the 

 ;anous Auction karyokineses that have been described. 



SUMMARY 



yt 



°ntains a linin network in which small chromatin granules are held, 

 ther se P*rate or in lumps. 



2 « At thp Ka^ : * «■• • t .1 1 ...i.' — o^miAc arp massed 



