34 
Latent and Semi-Latent Characters. 
Selection and nutrition have as usual a great effect 
on half races. I shall not deal exhaustively with this 
point until the end of this part, but will give here a brief 
discussion of the general principles underlying it in order 
to prepare a proper understanding of the question. 
Our discussion of the phenomena of fluctuating vari- 
ability in the third part of the first volume led us to the 
conclusion that selection and nutrition usually operate 
in the same manner on the individual characters of plants. 
Fig. 2. Influence of selection and nutrition on the half 
race Ranunculus bulbosus scmiplcnus. A, Half Curve 
after several years of culture. B, Curve of the 12 best 
individuals (i. e., those richest in petals). C, Curve of 
the best plant. 1 
Positive selection and plenty of food enhance the devel- 
opment of a character, whilst selection in a minus direc- 
tion or defective nutriment operate in the opposite direc- 
tion. 
Polycephaly in Papaver soinniferum behaves in this 
way, 2 and, as we shall see later on, all the other anomalies 
which have been tested do so, as well. Half curves can 
thereby be transformed into unilateral ones (Fig. 2) , either 
1 Ber. d. d. bot. Ges., Vol. XII, 1894, Plate X, Fig. 4. 
8 Vol. I, Part I, pp. I35-M3. 
