External Conditions and Manuring. 315 
site leaves to stems with trimerous whorls (Fig. 58 b 
and a). 
The arrow A in Fig. 58 indicates the result of im- 
proved conditions, the arrow B that of more unfavorable 
ones. 
The figure therefore not only illustrates a particular 
case but is a graphic representation of our thesis that 
high nutrition favors the production of the anomaly. 
This scheme can be applied to a long series of cases, 
both of anomalies that occur in the field and of highly 
variable horticultural varieties. The best known example 
is furnished by the tricolored pansy Viola tricolor ma- 
xima. Here, as every gardener knows, the spring and 
early summer flowers have larger, much broader and 
more intensely colored petals than those of late summer. 1 
The greater drought and the gradual exhaustion of ma- 
nure around the plants are the causes. The same general- 
ization applies to numerous cases to some of which we 
will refer in the following section. 
27. THE INFLUENCE OF EXTERNAL CONDITIONS AND 
OF MANURING. 
J. COSTANTIN has dealt with the relation between the 
plant and its environment in a book devoted to this ques- 
tion. 2 In it he treats of the influence of the environment 
both on the normal characters of the plant and also on 
varieties and anomalies. An immense range of facts and 
observations is thus made accessible to the student. 
1 V. B. WITTROCK, Viola-Studier, Acta Horti Bergiani, Vol. II. 
1897, Nos. i and 2. See also VERLOT, loc. cit., pp. 46-47. 
2 J. COSTANTIN, Lcs vcgctaux ct les milieux cosmiques. Bibl. 
scientif. Internationale, 1898. The earlier writings of this author 
have been dealt with in our first volume (p. 99). 
