2l6 
E. M. EAST 
should be justified in stating that comparatively starvation had no 
effect on the flowers. 
Both sets of these plants had a sufficient supply of moisture to 
keep them healthy. When this is not the case there is some difference 
in flower size. For example, some N. rustica plants each showing a 
mean flower length of 20 mm. with extremes of 18 mm. and 22 mm. 
at the first of the season, decreased in their mean flower length to 
18.8 mm. after being in flower for four weeks during which very little 
rain fell. Then came four inches of rain within forty-eight hours. 
After this, stout vigorous laterals arose from the lower part of the 
main stems bearing flowers with a mean length of 21.1 mm. (extremes 
were 19 mm. and 23 mm.). Thus a marked difference in activity of 
cell division shows its effect on the flower. 
This factor is probably the cause of the greater size shown by 
flowers on lateral branches when compared with those on terminal 
branches in Goodspeed's and Clausen's work (Tables XIII, XIV, XV). 
These authors also found that the flowers on new vigorous branches 
after "cutting back" were increased in the same way. 
These facts should be taken into consideration when examining 
the conclusion of the California botanists that flower size decreases 
markedly as the length of the flowering season increases. Their data, 
as well as my own, proving that flower size may keep up to that of 
the first of the season and even increase if the weather conditions 
remain favorable for the production of vigorous new lateral branches, 
show that it is questionable whether a significant decrease in flower 
size occurs during the time that data would be likely to be taken. 
Their data showing marked decreases from the first of the season to 
mid-season are from populations of 9 and 10. During similar periods 
I have found no 'measurable decrease in flower length in N. tahacuniy 
N. longiflora, N. paniciilata and N. rustica. I have found a mean 
decrease of i.o mm. to 1.5 mm. which possibly is due to this factor in 
certain cultures of N. langsdorffii, N. acuminata, N. forgetiana and 
N. alata grandiflora, but I think the true occasion of the decrease was 
lack of moisture. On the other hand, there seems to be evidence in 
Goodspeed's and Clausen's data that toward the end of the season 
there is likely to be a decrease in flower size. My own data have 
shown a drop of from 4 mm. to 8 mm. in both corolla length and 
spread in various species in the last dozen or two flowers produced. 
This shows as a sudden change which is evidently due to physiological 
