APHORtftMS ON THE FRONTAL SINUSES. 45 



Now these successive formations follow not an increasing disparti- 

 ^-ion of the bony plates themselves, but the removal only of their 

 intermediate cellular structure : consequently, the bone's horizontal 

 diameter or thickness receives no addition from this process of na- 

 tural excavation. Since, therefore, the size of these cavities does 

 not move the skull's external surface to a greater than its original 

 distance from the brain, before the prime of life, it is manifest that, 

 until this period at soonest, phrenological observation on the frontal 

 regions may be conducted with all the accuracy admissible by a sub- 

 ject whereon vital action never ceases to operate. Hence, in fine, 

 although difficulties occur in examining the forehead, they never 

 supervene before the positive recession of the bone's two constituent 

 plates from each other — not the extinction of its diplo'e — has given 

 the bone itself a growing degenerate thickness. The Frontal Si- 

 nuses very seldom ascend ah inch within the bone ; and through 

 the upper half of this space, their transverse diameter never exceeds 

 the thickness of the bone's original cellular substance. 



VIII. Such being the organization of the frontal bone generally , 

 and such the general development of its central cavities, it is obvious 

 that, in the young and healthy heady the distance of the bone's ex- 

 ternal surface from the corresponding ]»eripheral surface of the brain, 

 may be generally ascertained ; and, consequently, that the existence 

 and functions of the organs of Individuality, Size, Form, Weight, 

 and Locality, can be discriminated till after the prime of life, by 

 the phrenological process of deriving the elements of positive and 

 negative evidence, from observation of the high and low develop- 

 ment of parts. Be it, therefore, remembered that phrenologists 

 have always and explicitly declared, that persons advanced in years, 

 or suffering from cerebral disease, do not constitute subjects of pre^ 

 cise observation, — that the observations adduced by phrenologists in 

 support of their organic discriminations, have, in no one instance, 

 been made on such subjects, — and that, moreover, they have as ex- 

 plicitly declared their readiness, not only to rest the demonstration 

 of the frontal organs upon negative evidence, but even to admit a 

 fundamental defect in their system, on being shown one single ex- 

 ample of a young, healthy individual in whom a hrv development of 

 the organs of Individuality, Size, Form, Weight, and Locality, is 



