350 
G. ARCHIE STOCKWELL. 
exact science! Again, comparative medicine suffers from the i: 
norance of the masses; in spite of our boasted civilization, an 
individual, no matter how illiterate or brainless, is held competer 
to administer to the ills of animality, (and even humanity), an 
there appears to be implanted within every member of the liuma 
race an inherent desire to dabble with “physic” exhibited in ii 
verse ratio to the degree of intelligence. 
The canine ear differs less from the human than might at fir: 
be imagined from comparison of external characteristics of bot 
crania, consequently, under the supposition the latter maybe moil 
conveniently at hand, I select it for illustration. For all practic? 
purposes, it is only necessary to remember that the mastoid pr< 
cess in the dog is situate higher up than in man when viewed ii 
the same plane, a difficulty that may be overcome by lifting the po: 
tior portion of the human os temporis to an angle of 25 degree, [ i 
With this understanding that the human crania is selected merel; 
for illustration, and that the relations expressed are purely canine 
and referring to the larger animals, let us select the left tempore 
bone for convenience and definiteness. 
Starting with the external opening of the ear we first observ 
an annular leaf of osseous material, developed in varying degree 
in different subjects and species, curved underneath, and cemente 
anteriorly to the squamous portion, and posteriorly to the petron 
portion of the os temporis. Following the direction of the meaty 
auditorious externus , at its further extremity is encountered th 
drum or merribrana tympanic which preserves the same geneni 
character and relations in ail higher vertebrates save in the one facte 
of size. With a tendency downward and inward, and an inclinatio 
forward of about forty-five degrees, it presents the appearance of j 
firm, somewhat elastic, semi-transparent membrane, blocking tli 
way to the tympanum or middle ear. Beyond is found an apartmei 
of extreme shallowness (the middle ear) more lofty by one-hal 
than the meatus , some three lines in depth, and eight and a-liai 
in anteroposterior measurement. Midway between the floor an 
ceiling in the anterior wall, we find the opening leading downwarJ 
and inward to the posterior pharynx—the eustachian way. Nea 
the centre of the farther wall, opposite the drum, is the promotory 
