TRANSACTIONS OF SECTION K. 681 
Reduction Divisions (?) in Somatic Tissue. 
By RB. R. Gates, M.A., Ph.D. 
In connection with a study of somatic mitoses in the nucellus of Oenothera lata 
certain peculiar phenomena were observed in rare cases, indicating that a reduc- 
tion division was about to take place. 
Regarding normal somatic mitosis the following points may be mentioned :— 
(1) The number of chromosomes in the individual studied was 15, and it is not 
improbable that the extra chromosome is constantly associated with the O. lata 
characters. 
(2) The resting nucleus contains a uniform reticulum, with no indication 
whatever of bodies corresponding to prochromosomes. 
(3) The chromosomes are variously arranged when they arise from the 
reticulum, but they are not evidently paired, nor do they form a continuous 
spireme at any time. 
(4) Later in the prophase, and particularly in a polar view of the metaphase, 
they are often clearly in pairs side by side. 
(5) A conspicuous longitudinal split appears in the chromosomes in prophase, 
but afterwards closes up. Certain variations in chromosome number are ascribed 
to the precocious separation of the daughter chromosomes formed by this split. 
(6) In telophase the chromosomes pass through a transient stage in which they 
show a transverse median constriction, but there is no indication of any split 
before they pass into the resting condition. 
The chromosomes in certain cells were found to differ from their normal rod- 
like shape. 
Two nucellus cells were observed in which the spindle was much larger than 
usual, one spindle being as long as the heterotypic spindle in the megaspore mother- 
cell. The chromosomes on this spindle were several of them joined laterally to 
form close pairs or bivalents, the members of certain pairs being partly fused. 
The chromosomes were also oriented differently from their usual position on the 
spindle. 
The relatively great size of this spindle, together with the various peculiarities 
of the chromosomes, makes it probable that a somatic reduction division was 
about to take place. 
6. The Values of different Degrees of Centrifugal Force on Geotropic 
Stimuli. By W. EH. Hey, M.A. 
The method of obtaining these values is based on the same principle as 
Fitting’s intermittent clinostat. 
Seedlings are pinned to the back of the inside of a box which, when still, 
remains in a vertical position. The box is attached to a rod which can be made 
to revolve about its middle point, at about two hundred revolutions per minute, 
in a horizontal plane. When the rod is rotating the box automatically takes up 
a position so that the back lies in the line of the resultant of the centrifugal 
force and gravity, and in such a way that the centrifugal force would stimulate 
a bend in the radicles in the opposite direction to that stimulated by gravity 
- when the box is at rest. 
The centrifugal ‘ wheel’ is driven by an electric motor. By means of a clock 
whose arm dips into mercury through part of its course, the electric current 
driving the motor is made to pass only for regulated periods—say, one minute 
in every ten. 
Thus the seedlings in the box are subjected alternately to the stimulus of 
gravity in one direction and any prearranged centrifugal force up to 20g in the 
opposite direction. 
A successful experiment is one in which these two opposing stimuli neutralise 
each other, and the radicles of the seedlings show no ultimate bend in either 
direction, and it is then found that if C@ be taken as the centrifugal force 
which alternates with g (gravity), and if C be allowed to work for a period 7’, 
and g for a period ¢, then ('7'=gt, or, in other words, that the stimulating 
force (acceleration) multiplied by the time of action is the same in each direction, 
