80 
EARLY IMPREGNATION OF A HEIFER CALF. 
we shall not hesitate in acknowledging that the value of the 
created breed cannot be maintained by selection from that breed 
alone. The degeneracy may be slow, insensible, long unper¬ 
ceived, on account of the power which the pure blood has to 
repel contamination ; but that blood can only retard the tendency 
to retrograde; it can never altogether arrest the progress : that 
must be effected by occasional, and, perhaps, not unfrequent 
mixture of the pure blood. 
Another thing should not be forgotten, that the march of de¬ 
gradation having commenced, and no recourse being had to that 
by which alone its progress can be arrested, it will proceed with 
fearful and yearly increasing velocity. The table by which is seen 
the improvement of the race under the constant influence of 
pure blood, will also express the rapidity of the degradation. 
Supposing, finally, that a mare, that has approached to that 
degree of purity of blood which our table has given to the 30th 
generation is crossed by a horse of no breeding, and this system is 
carried on, the table will precisely express the rapidity of the 
degeneracy. At the 4th generation there will only be part of 
pure blood remaining ; at the 10th not a thousandth part ; and 
at the 20th not a millionth part. These are important truths, 
and deserve to be well considered. 
A CASE OF EARLY IMPREGNATION OF A HEIFER 
CALF. 
[The following brief account is extracted from a letter lately re¬ 
ceived from a valued medical friend, and amateur but scientific 
agriculturist in Gloucester. At no very distant time we hope 
to be permitted to append his name to some interesting and 
valuable communications.—Y.] 
By the way, I saw a curious thing a few weeks ago. A gen¬ 
tleman in my neighbourhood, who takes a great pleasure in breed¬ 
ing and feeding good stock of every kind, was rearing a heifer 
calf, a direct cross betw^een the short horn and Hereford; and 
which was nearly seven months old. She was obliged to be 
slaughtered, in consequence of thoracic inflammation, and in her 
uterus was found a full-formed male calf; I should say of three 
months. She had run with her dam in the field wuth the dairy- 
cows, and with a three-years-old bull, who was her sire, and by 
whom she must have been impregnated. She had never been 
observed to exhibit the usual oestrum. Is not this an unusual 
occurrence ? 
