514 
Rickets, Bone Softening and Paralysis 
removal of structure might follow, but ulceration I have not met 
with. The bones, as a whole, are not disposed to bend or alter 
in shape ; but from the thinness of their shell of compact tissue, 
thev are very liable to fracture under trifling exertion. The 
periosteum — bone-covering — is thickened throughout its entire 
extent ; the under-laver of active cells seems engaged in a forma- 
tive process somewhat similar to that which is observed in 
bone-production. The external surface of the bone-shaft is less 
smooth and polished than in healthy animals. Other bones of 
the skeleton, as the scapulae and pelvic bones, may in some 
instances give evidence of changes of a similar character. 
Symptoms. — Apart from the fatal results of this alteration of 
bone-structure, in fracture of bones, particularly those of the 
limbs, it can scarcely be said that there are any indications by 
which these changes may be detected during life. Following 
the occurrence of several such cases in a flock, carefully con- 
ducted examinations may detect indications of the local bone- 
change. Generally, however, to the ordinary observer no indi- 
cations of disease present themselves prior to the occurrence of 
fractured limbs. These rarely appear in numbers at one time, 
but are irregularly distributed over a lengthened period. The 
causes which seem to operate in their immediate development 
are apparently the most trivial. The occurrence of rain suf- 
ficient to thoroughly wet the ground, causing the animals to dip 
excessively in moving along, may thus operate. The rough 
handling of the flock with a dog, or any attempt to seize some 
for examination, may each lead to the production of a fracture. 
The more numerous instances I have noticed happen during 
moonlight nights, when sheep are easily disturbed, or, inde- 
pendent of disturbance, are disposed to gambol. The existence 
of stake-holes left in fields, from the shifting of hurdles or nets, 
are also fruitful causes of these fractures. In the fracture itself 
there are some slight differences from what occurs in a healthy 
bone when broken. It is attended with more effusion, and the 
immediately contiguous parts are at once more swollen, softer, 
and less well defined. Cases of compound fracture are much 
rarer than simple ones. Any attempts to produce reduction of 
the fracture and reunion of the parts are greatly more uncertain 
than in otherwise healthy animals. 
Treatment. — This, in so far as relates to treatment of the bone 
lesions, when these have occurred, is futile : carried out in the 
direction of preventi(m, it is tolerably successful. 
When from previous experience such a condition of the 
skeleton is apprehended as noted under this latter disturbance, 
the addition to their ordinary food, i.e. what is obtained 
from the lands on which they have been reared and are located, 
