SYNOPSIS OF VETERINARY CONTINENTAL JOURNALS. 623 
3. Periosteum in the normal state and in the adult subject 
exclusively repairs the wear and tear which life imposes on 
bones; when seriously injured, it loses its reparative and 
osteogenic power. That it may produce osseous substance 
in adults it must be either newly formed or irritated. In 
both these cases it cannot by itself produce a new bony sub¬ 
stance, since it is indispensable that it come into combined 
action with young cells, over which it may exercise its 
ossifying influence. Periosteum can cover-in long standing 
fissures without their self-obliteration. Ollier’s doctrine is 
here at fault. 
4. The physio-pathological processes of the elements 
enclosed in the Haversian canals are liable, as Billroth has 
said, to furnish an organisable exudate, but it is by no means, 
as that surgeon thought, to consolidate fractures, whether of 
long or of flat bones. The part which it was considered to 
play in uniting the fragments is purely imaginary. The 
exudate from the tissues and vessels of the Haversian canals 
does not in any respect differ from the matter thrown out by 
the parts around the fracture, such as the areolar, vascular, 
muscular, and tendinous structures. 
5. The process of consolidation of a fracture is not con¬ 
stantly effected in the same manner, but varies according to 
the nature of the fracture and the bone which is broken. In 
some cases it results from the periosteum of the new forma¬ 
tion and the exudate from the surrounding parts. In others 
it is due to the old periosteum, which has been irritated, and 
then the vessels of the bone furnish exudate and ossifiable 
elements. In others the periosteum remains inactive, and 
the partially or completely fractured bone is repaired by 
means of conversion into compact tissue of its cancellated 
structure. Often in this case there occurs a cementing 
or calcification rather than a true consolidation and regene¬ 
ration of the fractured bone, for calcareous elements are 
alone used; this occurs especially in flat bones. In cases of 
complicated fracture the different processes above described 
may co-operate in bringing about repair, each one performing 
its own share.” 
Giornale di Medicina Veterinaria Pratica , September and 
October, 1878.— On the Formation of Callus in Fractures of 
the Bones of Birds. By M. Rivolta.—The preceding work 
of M. Ercolani has not convinced M. Rivolta, who in his turn 
has undertaken experiments specially on the bones of birds. 
He fractured the tibia, metatarsus, ulna, and femur of young 
subjects and of adults. As in the preceding article we 
simply give his conclusions : 
