1836. ] Physiology. ae 
mentation (on page 370 and infra) do not seem to the reviewer 
to be borne out by the facts. On page 373 he says: “ The object 
of food-yolk, as is well known, is to enable the young to abbre- 
viate its development by having its food supplied, and being con- 
sequently able to skip some of its ancestral stages.” Instead of 
this being the fact, exactly the reverse is true, as has been shown 
by Balfour, Cunningham and myself—/John A. Ryder. 
PHYSIOLOGY. 
Some Nores on RECALCIFICATION oF Human Teera.!—The 
extent to which human development depends upon the proper 
utilization of food is such that any fact bearing upon the success 
of this process becomes of paramount importance. 
Living in a section of country where diet and drink are unusu- 
ally deficient in calcific elements, my attention was many years 
ago called to the analogous condition of the teeth of children in 
that region, which, as a rule, are characterized by a correspond- 
-ing deficiency in calcific elements. 
Rapid and remarkable changes also occur in the condition of 
the teeth of adults—almost in direct ratio to their changes of en- 
vironment in this respect. The “ baker’s bread” and other food 
Products in most general use by the inhabitants of the region near 
the Gulf of Mexico, and more especially by the inhabitants of 
cities, are largely divested of calcific elements, while the water 
used for potable purposes is almost exclusively rain water, which, 
though a good solvent, contains no mineral elements. 
The wonderful power of adaptation possessed by our race is 
Such that people, living in this region for a number of generations, 
acquire the power of appropriating, from the meager supp'y thus 
furnished, the necessary elements to produce fairly good teeth ; but 
the very large number of residents, not natives of this section, 
whose early life and the life of their ancestors, has been spent in 
regions where calcific elements were more abundant, and whose 
Constitutional habit was accustomed to that abundance, are not 
able to assimilate, out of this meager supply, the requisite propor- 
tion of limesalts. ey, 
The function of nutrition being dual in its character—removing 
effete and worn-out material on the one hand, while supplying 
the elements to maintain the integrity of the tissues on the other 
—the calcific elements, which form the inorganic basis of tooth- 
Substance, and which rendered the teeth hard and firm, are car- 
ried away, while the supply to rebuild, being deficient in quantity, 
the corresponding amount is not restored, the teeth in conse- 
quence soon become decalcified and softened, falling an easy prey 
to unfavorable conditions. 
"Read before Sections F and H in joint session, Buffalo Meeting A. A. A. S., 
oe | 1886, A ek 
