Ranunculus Bulbosus Semiplenus. 261 
so give rise to a less steep curve, just as in the experiment 
under consideration. 
I made a corresponding experiment in the summer of 
1891, on the effect of manured and unmanured garden 
soil, with the race which was by that time considerably 
improved (Fig. 51 and page 250). The manuring was 
done with guano ; the two beds lay next to one another 
and were of the same size. On each was sown half of 
the harvest of several plants which had been very pro- 
ductive of pleiopetalous flowers in 1890. In the course 
of the summer 1 59 flowers on the unmanured bed opened 
and were recorded and 376 on the manured. The rela- 
tion between these two numbers is the best measure of the 
effect of the manure. The results, reckoned in percent- 
ages, are as follows: 
Petals: 5 6 7 8 9 10 11 12 13 14 
Without manure: 12 15 25 21 12 10 3 1 1 
With guano: 14 15 17 21 14 9 4 3 2 1 
Without manure the apex of the curve was over the 
7 and there were very few flowers with more than eleven 
petals : with manure the apex was over the 8, and there 
were distinctly more pleiopetalous flowers. 
In both the above experiments the control material 
consisted of other individuals than those used for the 
experiment itself. It is possible, however, to subject the 
same plant alternately to favorable and unfavorable in- 
fluences, and when this is done the same result is ob- 
tained as in the previous cases. With this object I trans- 
planted a series of the best plants of 1892 to a very dry 
bed in the spring of 1893. I left them there, and did 
not water them although the weather was continually 
dry. They suffered visibly under this treatment and 
some of them even produced fewer flowers than in the 
