GENERAL PRINCIPLES APPLICABLE TO THE STUDY OF ALL THE BONES. 21 



law there are nmnerous exceptions ; and in order to demonstrate that it is not 

 absolute, it is sufficient to indicate that the direction of the nutrient foramen 

 varies much, not only in similar bones of different species of animals, but also in 

 similar bones of the same species^ ; and yet the progress of ossilication is alwajs 

 the same. 



The period when fusion of the epiphyses terminates in the domestic animals 

 is still little known ; fusion is evidently complete when growth is achieved, but 

 this period is markedly modified by hygiene and the :'ood animals receive. Renault 

 and some breeders have observed, that in the proocious breeds of cattle the 

 evolution of the teeth is more rapid than in the common breeds. More recently, 

 Sanson has affirmed that precocity, characterized by this prompt dental evolution, 

 is marked by a more rapid fusion of the epiphyses, and he believes there is a 

 direct relation between the evolution of the teeth and that of the bones. 

 According to this principle, in the Horse the fusion of the epiphyses should 

 commence and terminate between three and five years of age. 



Toussaint, however, did not share this opinion. In the Ox, Sheep, and 

 Horse, he remarked that the first centres of ossification appeared in the body 

 of the flat and the longbone^and in the centrum and arches of the vertebrae. 

 When the first half of ^esrajtionnad not been passed, no other points of ossifica- 

 tion were seen. It is necessary to add, however, those of the second and third 

 phalanges and the calcis, which comport themselves as long bones. 



In the last half of gestation, ossification invades the complementary nuclei, as 

 well as the short bones ; the exceptions are the pisiform bone and the inner condyle 

 of the humerus in the Calf and Foal, and the large and small sesamoid bones in 

 the Calf only. Ossification of these bones of the skeleton is slow. It must also 

 be mentioned that at birth the complementary nuclei of the coxas^ are not yet 

 visible, and they are net seen until ten months or a year afterwards. ^^ ^ ""' ^^^J 



With regard to fusion of the epiphyses, it occurs at the following periods in 

 the principal bones of the Horse ; at the twelfth to the fifteenth month in the 

 second phalanx at first, then in the first phalanx ; at the fifteenth to the 

 eighteenth month in the middle metacarpal, afterwards in the metatarsal. At 

 this age fusion also occurs at the upper end of the radius and inferior ex- 

 tremity of the humerus : from twenty months to two years, at the lower end of 

 the tibia ; from three to three and a half years, at the upper extremity of the 

 humerus, at the two ends of the femur, and at the upper end of the tibia ; 

 lastly, about five years, in the bodies of the vertebrae and in the coxae. 



In the Ox, ossification progresses at about the same rate as in the Horse, 

 except that there is a little greater precocity in the fusion of the epiphyses of the 

 humerus and radius, which are fused at the same time as those of the phalanges, 

 and matacarpal and metatarsal bones. In this animal, the two lateral halves of 

 the latter bones are united before union of the inferior epiphysis to the body of 

 the bone. The Sheep offers an interesting peculiarity, in that the humero- 

 radial epiphyses are consolidated before those of the phalanges, and towards the 

 tenth month. 



If the results of these observations, made on our principal domestic animals, 

 are compared with the evolution of the dental system, we are compelled to con- 

 clude, with Toussaint, that fusion of the epiphyses does not commence at the 

 same time as the eruption of the first permanent teeth. If a relationship exists 

 between the evolution of the teeth and that of the bones, it has yet to be 

 demonstrated in an exact manner. 



