44 Latent and Semi-Latent Characters. 
ing generally, favorable conditions favor the characters 
O O J ' 
of the race, and unfavorable ones those of the species (see 
below, 26). 
This is only a special case of the well-known prin- 
ciple : Every injury increases the tendency to atavism . l 
In the first place let us consider the periodicity. The 
number of multipartite leaves increases with the indi- 
vidual strength both on the whole plant and on the sep- 
arate branches. And if, at the end of growth, weakness 
supervenes this number again decreases. 
Let us examine Fig. 5. It is a photograph of a strong 
young branch which was removed on August 1, 1900. 
The lowest leaf was nearly withered ; it was small and 
had the inversely egg-shaped form of the leaflets which 
is characteristic of the leaves of the young red clover, 
It consisted of only 3 leaflets. The two following leaves 
were markedly larger and stronger, of a more elliptical 
form and tetramerous. Then follows a 6- and then a 
7-merous leaf, after which the leaves again return to the 
simpler types. 
The branch photographed was chosen for its regu- 
larity; and yet a pentamerous leaf is absent from the 
ascending series. Most of the branches, even on the best 
plants, were less regular : indeed it often happened that 
tetramerous leaves were succeeded by some trimerous 
ones, and so forth. 2 
What has been stated concerning the lateral branches 
is also true of the rosette of radical leaves whose axis 
1 That is, reversion of the race to its parent species, for the char- 
acter of the race is itself, morphologically speaking, a reversion to 
a more remote ancestor. 
2 For exact figures the reader is referred to : Ueber die Periodici- 
tat der partiellen Variationen, in Ber. d. d. bot. Ges., 1899, Vol. XVII, 
p. 48. 
