38 Professor Owen on the [Feb. 9, 



species of animals by gradual transmutation of specific characters, 

 and that in the ascending direction, Professor Owen admitted that the 

 skeleton may be modified to a certain extent by the action of the 

 muscles to which it is subservient, and that in domesticated races 

 the size of the animal may be brought to deviate in both directions 

 from the specific standard. By the development of the processes, 

 ridges, and crests, and also by the general proportions of the bones 

 themselves, especially those of the limbs, the human anatomist 

 judges of the muscular power of the individual to whom a skeleton 

 under comparison has appertained. 



The influence of muscular actions in the growth of bone is more 

 strikingly displayed in the change of form which the cranium of 

 the young carnivore or the sternum of the young bird undergoes in 

 the progress to maturity ; not more so, however, than is manifested 

 in the progress of the development of the cranium of the gorilla 

 itself, which results in a change of character so great, as almost to 

 be called a metamorphosis. 



In some of the races of the domestic dog, the tendency to the 

 development of parietal and occipital cristae is lost, and the cranial 

 dome continues smooth and round from one generation of the smaller 

 spaniel, or dwarf pug, e. g. to another ; while, in the large deer- 

 hound, those bony cristae are as strongly developed as in the wolf. 

 Such modifications, however, are unaccompanied by any change in 

 the connexions, that is, in the disposition of the sutures of the 

 cranial bones ; they are due chiefly to arrests of development, to 

 retention of more or less of the characters of immaturity : even 

 the large proportional size of the brain in the smaller varieties of 

 house-dog is in a great degree due to the rapid acquisition by the 

 cerebral organ of its specific size, agreeably with the general law 

 of its development, but which is attended in the varieties cited by 

 an arrest of the general growth of the body, as well as of the 

 particular developments of the skull in relation to the muscles of 

 the jaws. 



No species of animal has been subject to such decisive experi- 

 ments, continued through so maSiy generations, as to the influence 

 of different degrees of exercise of the muscular system, difference 

 in regard to food, association with man, and the concomitant stimulus 

 to the development of intelligence, as the dog ; and no domestic 

 animal manifests so great a range of variety in regard to general 

 size, to the colour and character of the hair, and to the form of the 

 head, as it is affected by different proportions of the cranium and 

 face, and by the intermuscular crests superadded to the cranial 

 parietes. Yet, under the extremest mask of variety so superinduced, 

 the naturalist detects in the dental formula and in the construction 

 of the cranium the unmistakeable generic and specific characters of 

 the canis familiaris. This and every other analogy applicable to 

 the present question justifies the conclusion that the range of variety 

 allotted to the chimpanzee under the operation of external circum- 



