in Lambs and Youvg Sheep. 
513 
viz. as merely a local affection resulting from changes in the 
medullary as well as compact tissue of bone. From the fact, 
however, that prevention may be secured by a properly regulated 
diet, this latter view appears less tenable than the other. 
Causation. — Like the previous manifestation of defective 
bone-nutrition spoken of as affecting lambs, this, as respects the 
simple recognition of the conditions which, when brought to 
bear on young sheep, operate in inducing fragility and softening 
of bone-tissue, is easy enough. It is when we come to par- 
ticularise the steps by which the disturbed nutrition is reached, 
that we meet with difficulties. The conditions under which 
fragility of bones in young sheep is met with are characters of 
soil, and food-production, precisely similar to what have already 
been noticed in the previous disturbance appearing in lambs. 
The continuance of this disease, or its liability to occur when 
started, seems to be governed by the relations of proximity to 
the period of cultivation, and the application of lime exactly 
similar to what has been already mentioned. So well known to 
the majority of sheep-farmers is this tendency of these already 
mentioned lands, when treated as described, that the dread of the 
occurrence of one or other of the diseases now under considera- 
tion operates largely in restricting the breaking-up and the 
improving of them. In both these forms of disturbance of 
bone-nutrition, we may speculate as to the rationale of the 
action by which the ingestion of food produced from such soils 
operates in inducing the changes ; but until further chemical 
and experimental investigation has been carried out, we have 
little solid ground on which to stand. 
Anatomical Characters. — By far the most marked, indeed, the 
only obvious, structural changes are in connection with the 
bones of the extremities. These, along with their covering 
membrane, give to the ordinary observer the idea of increased 
vascularity. There is not, however, as in ordinary rickets, any 
increase in bulk or extra development of the extreme ends 
of the bones, nor are the changes greater at their junction 
with the shaft. The outer shell of compact tissue does not 
appear unnaturally softened, only unnaturally thinned, the 
medullary canal being of greater capacity and the open tissue 
increased. Extending into the interstices of this tissue and 
throughout the medullary canal, there is an abundance of soft 
reddish pulp, largely made up of fat globules, nucleated cells, 
and blood corpuscles. This material, while extending into 
the extreme ends of the bones, does not induce any evident 
increase of bulk in these parts. The articular cartilages, 
although not destroyed, seem thin, and are spotted over their 
centres with dark-coloured markings. These look as if 
