1866. | Darwin and his Teachings. 161 
the common belief of agriculturists in analogous cases, that the niata 
cow when crossed with a common bull, transmits her peculiarities 
more strongly than the niata bull when crossed with a common cow. 
When the pasture is tolerably long, the niata cattle feed with the 
tongue and palate as well as common cattle; but during the great 
droughts, when so many animals perish, the niata breed is under a 
great disadvantage, and would be exterminated if not attended to; 
for the common cattle, like horses, are able just to keep alive, by 
browsing with their lips on. twigs of trees and reeds; this the niatas 
cannot so well do, as their lips do not join, and hence they are found 
to perish before the common cattle. This strikes me asa good illus- 
tration of how little we are able to judge, from the ordinary habits of 
life, on what circumstances, occurring only at long intervals, the 
rarity or extinction of a species may be determined.”* 
We have extracted these two paragraphs at length, from his 
‘Journal, to show that more than twenty-five years before the 
appearance of his great work on the ‘ Origin of Species,’ Darwin’s 
attention had been directed to, or, we should say, arrested by 
phenomena similar to those which he imported into that work 
in which we find no mention of either phenomenon although both 
would well have served to aid him in proving his theory; and we 
believe our zoological readers will agree with us that facts stated 
so unpremeditatedly are far more valuable than others selected by 
the author for the purpose of proving a point. Again, our readers 
will find, if they take the trouble to refer to his ‘Journal,’ that 
it contains much valuable information bearing upon the changes 
which have been effected in animals through migration, for through- 
out there are repeated evidences of variation in structure and habit 
being favoured by this cause. : 
One striking instance of this unconscious accumulation of 
evidence in favour of his subsequent convictions and, at the same 
time (if we rightly interpret his meaning), of his unbelief at that 
time in the transmutation theory, will be found in his account 
of the variation of species on either side of the Cordillera.t He 
shows that the species on the two opposite sides of this range are 
distinct but allied, although the climate, soil, and longitude and 
latitude may vary but little, and he attributes this variation to the 
barrier thus opposed to the migration of all but a few animals. 
In a note he says:—‘ This is merely an illustration of the admi- 
rable laws first laid down by Mr. Lyell, on the geographical 
distribution of animals as influenced by geological changes. The 
whole reasoning, of course, is founded on the assumption of the 
immutability of species, otherwise, the difference in the species in 
the two regions might be considered as superinduced during a 
length of time.” 
Of* course, in his new doctrine, he does believe that the 
* «Journal of Researches, pp. 146-7. + Ibid., pp. 326-7. 
