15 
Raineses II., — and at Karnak, among heads which are repre- 
sented as smitten by Sethos I., — we find Negroes true to their 
present type in all particulars. If, then, the whole Negro 
variety had been climatologically thrown off from the parent 
stock between the Flood and the time of Moses or Joseph, 
that interval must have greatly exceeded all our conceptions 
of the period as derived from the pen of Moses, — an apparent 
discrepancy between Scripture and scientific research which I 
have no wish to establish, if, by adopting any other theory, 
all the phenomena of the case can be otherwise satisfactorily 
explained. 
25. It may possibly be urged that the influences of climate 
were at that time much more likely to develop, physical 
changes in man with rapidity than they have been since. But 
every candid mind will acknowledge that this is mere specula- 
tion, and that in arguments of a scientific nature all speculation 
ought to be dismissed which cannot be rendered probable by 
some form of presumptive proof. I go forward, therefore, into 
other grounds of observation, with a view to see whether 
we cannot find certain processes of nature, through which 
physical varieties can be now produced, which are quite as 
divergent from the ordinary types of animal life as the Negro 
variety is from the rest of mankind. 
26. For this purpose let us look into (IY.) The Eepect op 
Systematic Weeding, under the Principles op Methodical 
Selection. 
27. Every one who has studied Natural History must be 
aware that new varieties of animals may be artificially pro- 
duced by crossing breeds through carefully-selected pairs. I 
shall first illustrate this fact, and afterwards consider whether 
such a class of phenomena can be fairly adapted to any other 
theory of Negro origination. 
28. Perhaps the best illustration of this part of the subject 
may be taken from the family of swine. All the known breeds 
of swine may be divided into two groups : the one group 
going by the name of Sus Scrofa , and the other of Sus Indica , 
between which breeds there are well-known differences, 
especially in the conformation of their skulls. Now, as a 
matter of fact, it is found that when any two of these opposite 
breeds are crossed, the one so modifies the other that the 
greatest changes are very quickly produced. It is stated, 
indeed, by one of the very best authorities,* that -^-nd part of 
the blood of the Sus Indica infused into a breed of the Sus 
Scrofa is sufficient to produce a distinct modification of the 
* Nathusius, Schiveinschadel, s. 138. Quoted in Darwin’s Variations of 
Animals and Plants, vol. i. p. 69. 
