326 THE DOCTRINE OF DESCENT. 
opposite poles. Kélliker (p. 44) thus sums up his fundamental 
view— that in and with the first origin of organic matter and of 
organisms, the whole plan of development, the collective ‘series of 
possibilities, were also potentially given, but that various external 
impulses operated determinatively on individual developments, and 
impressed a definite stamp upon them.” Notwithstanding the 
scientific dress, dualism is here complete; whereas, Physics and 
Chemistry make their laws, applying to inorganic as well-as to 
organic nature, comprehensible in their form, purport, and effects, 
Killiker knows nothing of the constitution of his laws. The 
doctrine of natural selection allows us to recognize the causes and 
effects of heredity and adaptation, and establishes the phenomenal 
series under the form of laws. But laws which are founded only 
on a plan which is to be carried out prospectively and in subser- 
vience to this dower of imperfect organisms, are ignored by natural 
science. 
69 Ueber die Herkunft unserer Thierwelt. Einezoo-geographische 
Skizze von L. Riitimeyer (Basel, 1867). We have made copious 
use in our text’ of this extremely instructive writing. 
70 A. R. Wallace, Malay Archipelago. P. 10, &c. 
71 G, Koch, Die indo-australische Lepidopteren-Fauna in ihren 
Zusamnenhang mit den drei Hauptfaunen der Erde. (1 Ed. Ber- 
lin, 1873.) 
72 Peschl, Neue Probleme der vergleichende Erdkunde, 1870. . 
75 All the more distinct -is the affinity of the Mastodon and the 
Elephant. Between the pliocene Mastodon Borsoni and the Elephas 
primigenius, twenty species are interposed, among which are our 
still living species, the Indian and African elephants. The limits of 
the two genera are hereby entirely obliterated. According to 
other statements, the Elephas primigenius (the mammoth) falls 
into at least four geographical varieties, which join on to the 
American species. A dwarf species of elephant is found in the 
caves of Malta, which in dentition attaches itself to the African 
species. 
7! Joh. Schmidt, The Relationships of the Indo-Germanic Lan- 
guages, 1872. 
75 Various antagonists of the doctrine of descent have vented 
their moral dismay in the most poignant expressions, precluding 
