526 
Reginald Euggles Gates 
in 1907, had in August, 1907, published a note stating tlie number 
of ckromosomes in root tips of 0. gigas to be 28 or 29. 
An account of the method of chromosome reduction in Oenotbera 
bas already been published (Gates 1908 b) based cliiefly upon studies 
of 0. rubrinervis , but supported by observations upon a more or less 
complete series of stages in several otber forms, including 0. La- 
marckiana, (). nanella, 0. lata x 0. Lamarckiana, and more re- 
eently 0. laevifolia and 0. biennis (Gates 1909). Furtker results 
upon some of tbese forms, as well as upon tbe Ü. lata X O. gigas 
bybrids, will be published soon. Tbey agree in praetically all points, 
as regards the phenomena of reduction, witli the account already 
published for 0. rubrinervis. 
1. Cytological observations. 
In 0. gigas the stages of reduction in the pollen mother cell 
thus far observed are continuous only during the period from the 
metaphase of the keterotypic mitosis to the prophase of the komo- 
typic. These events are in substantial agreemeut with those already 
described for 0. rubrinervis (Gates 1908 b), but a few deviations 
will be referred to. Fig. 1 shows the keterotypic spindle in side 
view. As previously described for the otker forms studied, the 
ckromosomes are loosely scattered in the middle region of the 
spindle, rnostly unpaired, or at anv rate not closely enough paired 
to make it evident wkieh members constitute a pair. A large number 
of spiudles examined at this time almost iuvariably show this con- 
dition. It cannot then be due to the fact that this figure represents 
a stage just before the ckromosomes kave been drawn into the equa- 
torial plane or just after they have begun tkeir journey towards the 
poles. Fig. 2 is exceptional in that most of the ckromosomes are 
ratker regularly arranged in two parallel rows and they are scat- 
tered tkrough a shorter distance along the longitudinal axis of the 
spindle than usual. They are separating into two ratker regularly 
oriented groups of ckromosomes on tkeir way to the poles. In this 
cell the forces which lead to the regulär alignment of the ckromo- 
somes in two parallel series are evidently strenger than is usually 
the case in Oenotliera, for in the Oenotbera forms studied, usually 
no such regulär alignment takes place. 
The absence or partial abscnce of a close pairing of ckromo- 
somes in diakincsis and on the keterotypic spindle is in strong cou- 
