The Biochronic Equation. 063 
changed, are usually designated, amongst paleontologists, 
as mutations. 1 The name varieties is applied by them to 
those forms which live side by side at the same time and 
constitute the rays of a fan or the units of a swarm in 
our diagram in Fig. 149. In this sense my Oenotheras 
are related to one another as varieties, but to the parent 
form as mutations. In experimental science, however, 
these paleontological terms would prove very incon- 
venient; and the older meaning of the word "mutation," 
as it was used by botanists long before WAAGEN, is 
greatly to be preferred. What varieties are, will for a 
long time remain a topic of discussion. 2 
14. THE BIOCHRONIC EQUATION. 
The characters of organisms are not unlimited in 
number. However complex the structure of a higher 
plant or animal may seem, and however much the char- 
acters which compose them may give the impression of 
being unlimited, no one will deny that, when more closely 
examined, their organization will appear, although not 
simple, at least a great deal simpler than it seemed to be 
at first sight. 
COPE states that for the 28,000 species of vertebrates 
there are only a few hundred organs on which their varia- 
tion and diversity rests. 3 If we examine the dichotomous 
tables for the identification of species in the most various 
groups of animals and plants, AVC are astounded at the 
1 See H. E. ZIEGLER, Ucber den derzcitigcn Stand der Descendens- 
Ichrc in dcr Zoologie, Jena, 1902; and the same in Zool Centralblatt, 
1902, Nos. 14-15. 
See above 3, p. 578. SAGERET defined mutations as "Varietes 
qui se fonncnt sous nos yeiix." Ann. Sc. not.. 1826. p. 299. 
: E D. COPE, The Primary Factors of Organic Evolution, 1896. 
