150 ILLUSTRATIONS OF THE SIGNIFICANCE OF 
stant pressure on the occiput during the whole protracted period of 
nursing, when they are peculiarly sensitive to external influences. 
Experiments have shewn that at that period the bones specially affecte 
ed by the action of the cradle-board are not only susceptible of chan- 
ges, but liable to morbid affections, dependent on the nature of the in- 
fant’s food. Lehmann supposes the craniotabes of Elsisser to be a 
form of rachitis which affects the occipital and parietal bones during 
the period of suckling; and Schlossberger ascertained by a series of 
analyses of such bones that the 63 per cent- of mineral constituents 
found in the normal occipital bones of healthy children during the first 
year, diminished to 51 per cent. in the thickened and spongy bone.* 
The fluctuations in proportion of the mineral constituents of bones are 
considerable, and vary in the different bones, but in the osseous tissue 
they may be stated at from 67 to 70 per cent. It is obvious, there- 
fore, that, under the peculiar physiological condition of the cranial 
bones during the period of nursing, such constant mechanical action 
as the occipital region of the Indian pappoose is subjected to, must be 
productive of permanent change. The child is not removed from the 
cradle-board when suckling, and is not therefore liable to any counter- 
acting lateral pressure against its mother’s breast. One effect of such 
continuous pressure must be to bring the edges of the bones together, 
and thereby to retard, or arrest the growth of the bone in certain dir- 
rections. The result of this is apparent in the premature ossification 
of the sutures of artificially deformed crania. 
At Washington I had an opportunity of minutely examining thirty- 
four Flathead skulls brought home by the United States Exploring 
Expedition ; some of them presenting the most diverse forms of dis- 
tortion. In the majority of those the premature ossification of the su- 
tures is apparent, and in some they are almost entirely obliterated.— 
The same is no less obvious among the corresponding class in the col- 
lection of the Academy of Natural Sciences of Philadelphia ; and es- 
pecially in skulls of the Chinooks, who carry the process of deforma- 
tion to the greatest extent. But I have also been struck, not only 
with the frequent occurrence of wormian bones in such altered skulls, 
but also with the distinct definition of a true supraoccipital bone. 
It is marvellous to see the extraordinary amount of distortion to 
which the skull and brain may be subjected without seemingly affecting 
either health or intellect. The coveted deformity is produced partly 
* Schlossberger. Arch, f. phys. Heilk. Lehmann, Physiol. Chem. Vol. III. p. 28. 
