24 
Hereditary Diseases of Sheep and Pips. 
pretty poetic fancy, is inadequate to explain satisfactorily such 
cases as the above. It must not, however, be inferred from 
this remark tliat the imaoination has no power in affecting 
ioetal development. On the contrary, it can be easily shown 
that mere sensuous impressions acting on the female at the time of 
impregnation, or even during ])regnancy, are sometimes capable 
of affecting the offspring. Mares and bitclies frequently produce 
offspring differing from the sire, but resembling in colour and 
appearance those animals with which the mother has been kept, 
or of which she has been fond. George Combe mentions a 
case in which two horses were got with pretty markings of a 
very uncommon kind, by leading a horse having such markings 
Ijefore two mares just prior to their being covered. The parents 
in each case were different, but the young horses were so similar 
in colour that they could scarcely be distinguished from each 
other, and both had the same markings as the horse that was led 
l)efore the mares at the time they were impregnated.* Similar 
illustrations of tlie influence of the imagination are common among 
dogs ; and Mr. Milne has recorded, in the Transactions of the 
Linna?an Society, the case of a pregnant cat, which got a severe 
injury of the tail from a tread, and gave birth shortly after to five 
kittens which were perfect in all respects except that " the tail was 
distorted near the end and enlarged into a cartilaginous knob."t In 
the human subject, idiotcy, peculiarities of physical development, 
and physical deformities have been traced to mental impressions 
made on the pregnant mother.| It is evident, however, that, 
among the lower animals, the imagination is less powerful and 
excitable, and less capable of extended action, than in the human 
subject ; and we may tlierefore believe that it does not, in the 
majority of cases, affect foetal development, except by occasionally 
causing but slight alteration in colour or external form. 
II. Hereditary Defects and Diseases of Sheep. — The hereditary 
diseases of sheep have as yet been but little studied, probably on 
account of these animals being usually considered scarcely worthy 
of medical treatment, and of their being slaughtered at a com- 
paratively early age, and before much time has been allowed for 
the development of many diseases. But from what little infor- 
mation we have on this subject, there is no doubt that when any 
of the diseases, which are hereditary among men or the lower 
animals, occur in sheep, they will in them likewise prove here- 
ilitary. Diseases of this nature are often engrafted on previously 
healthy stock by neglect and mismanagement; fen- although at 
first accidental and acquired, they are almost certain to become 
* Combe's Constitution of Man. Fourth Edition, p. 104. 
t Blaine's Canine Pathology. Fourth Edition, p. 48. 
X AVhitehead on Hereditary Diseases, pp. 14-20. 
