512 
GENETICS: J. ZINN 
The ratio between the normal and abnormal flowers was found to be a 
function of the environment. Under a given set of environmental con- 
ditions this ratio as well as the relationship between the different forms 
of abnormal flowers inter se is constant to a very marked degree. 
Selection carried out for five years had no visible effect upon the type 
and range of floral variations of this race. The ever-sporting strain after 
isolation at once displayed the highest degree of abnormaHty ever reached 
in the subsequent generations under similar conditions of environment. 
Under conditions controlHng the intensity of abnormal development, 
optimum nutrition or starvation, while affecting the habit of the plant, 
appeared to have no effect upon the degree of manifestation of floral 
abnormaHties. The evidence from the study of this race under different 
conditions of environment points to high humidity and temperature as 
the factors favoring the expression of abnormality. Under conditions 
void of optimum humidity and temperature, the influence of starvation 
and lack of water upon the degree of abnormal development was 
noticeable. 
The results of a study of the frequency distribution of the different 
types of flowers upon the plant point to the existence of a definite region 
on the plant in which the tendency to vary and proHferate is most pro- 
nounced. Considering the plant as a whole, this region is confined to 
the basal, differentiated parts of the plant. The frequency distribution 
given in table 4 shows that the first three branches on the main stem 
from below, especially the second one, mark the seat of greatest abnor- 
mal development while the racemes in the axils of the 4th, 5th, and 6th 
branch show a low degree of variabiHty as well as the lowest absolute 
number of flowers. 
Similar but more marked differences prevail in the individual branches 
of the second and third order. Here it is again the buds in the axils of 
the second leaf and in the basal region of the terminal raceme that show 
the greatest relative number of abnormal flowers as well as the greatest 
range of variability as measured by the frequency occurrence of the 
most aberrant variants. 
Relative to the frequency occurrence of the different types of flowers 
at different periods of the flowering season, under the conditions prevail- 
ing in the greenhouse the first and second week of the flowering season 
mark the lowest relative production of abnormal flowers, after which a 
marked increase in the output of abnormalities follows when the second- 
ary and tertiary branches begin to develop their flowers. Towards the 
end of the flowering season the upper regions of the plants produced only 
