VARIATION IN DOMESTIC ANIMALS 455 
the highest possible degree. It is necessary, therefore, to exercise unusual 
judgment in comparing the records of recent years,whether of race track 
or dairy, with those which have been made a number of decades ago. 
With reference to dairy cattle it is possible to make some very interest- 
ing comparisons, first of old records as compared with those of the present 
day, and second of records of cows of uncertain breeding at the present 
time with those of cows of established dairy breeds. Thus Pearl has 
unearthed the record of a scrub cow owned by Mr. George A. Scott, of 
Nashville, Tennessee, which in 1863 produced about 12,450 pounds of 
milk. The record of an Old Sussex cow for the 5 years beginning in 1805 
is given in Table LVIII. In recent years a grade Jersey cow produced 
in 1 year 16,286 pounds of 
milk, the butter fat con- Tasie LVIIIl.—Propuction or MILK anv Burrpr 
tent of which, 844.8 pounds, By A Cow or THE OLD SussEex Breep, 1805- 
was equivalent to 1056 a 
pounds of 80 per cent. oe Weeks | Pounds | Pounds 
butter. At the time this aa cereal ene segiesh| ea aie 
record was made, it had ,. 
i: i aed b 1 HITS tera teers | 48.0 10,580 540 
See CEO ear sor) USeConds ss. eis nae | 45.5 | 8,895 | 450 
four cows within the Jersey Third..............) 51.5 | 12,367 | 675 
breed itself. Scrub cow Fourth............ | 42.5 9,071 | 466 
No. 131 in the government TR Nee toree ad Le eae | 48.0 11,548 594 
her hi | 
erd at Washington, an Totals...........| 235.5 | 62,456 | 2,725 
old cow between 15 and 
20 years of age, was in Averages... 47.1 | 10,491 | 545 
milk continuously from 
October 6, 1909 to August 
1, 1913, during which time she produced 33,066 pounds of milk. It 
appears, therefore, clearly to be established that so far as milk yield goes 
much of the improvement of late decades may have depended upon 
better methods of care and feeding; for over a century ago cows of very 
great excellence in this respect were produced occasionally, and at the 
present time cows of mongrel breeding may sometimes exhibit high 
performing ability. Undoubtedly, however, there has been an enormous 
multiplication of the best yielding families during recent years, even 
if there may not have been any actual increase in dairy potentialities. 
Obviously modifiability may act in a variety of ways. An interesting 
specific instance in dairy cattle is reported by Kildee and MeCandlish. 
At the Iowa Station a comparison was made between seven cows of 
mongrel breeding, and reared under unfavorable environmental condi- 
tions, with seven calves, their offspring, of the same type of breeding 
reared under favorable conditions since birth. The seven developed 
scrubs, that is, those which had been reared under favorable conditions 
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