DEVELOPMENT OF THE TEETH. 297 



is well known, the tallest children are frequently the weakliest. According to 

 Mr. Saunders, the degree of advance of the Second Dentition may be regarded 

 as a much more correct standard of the degree of general development of the 

 organic frame, and of its physical powers; and it appears from his inquiries, that 

 it may be relied on as a guide to the real age, in a large proportion of cases; 

 whilst no serious or injurious mistake can ever arise from its use. It may happen 

 that local or constitutional causes may have slightly retarded the development 

 of the Teeth ; in which case the age of the individual would rather be under- 

 estimated, and no harm could ensue : on the other hand, instances of premature 

 development of the Teeth very rarely, if ever, occur ; so that there is no danger 

 of imputing to a Child a capability for exertion which he does not possess, as 

 the test of height is continually doing. Moreover, if such an advance in Denti- 

 tion should occur, it might probably be regarded as indicative of a corresponding 

 advance in the development of the whole organism ; so that the real capability 

 would be such as the teeth represent it. 



291. The following is Mr. Saunders' s statement of the Ages at which the 

 " permanent" Teeth respectively appear. The first true Molars usually make 

 their appearance towards the end of the 7th year. Occasionally one of them 

 protrudes from the gum at 6, or more frequently at 6^ years of age; but the 

 evolution of the whole of them may be regarded as an almost infallible sign of 

 the Child's being 7 years old. In other instances, where the tooth on one side 

 of the mouth is freely developed, it is fair to reckon the two as having emerged 

 from their capsule ; since the development of the other must be considered as 

 retarded. This rule only holds good, however, in regard to teeth in the same 

 row ; for the development of the teeth in either jaw must not be inferred, from 

 that of the corresponding teeth in the other. With this understanding, the 

 results of the application of the following table will probably be very near the 

 truth. 



Central Incisors developed at 



Lateral Incisors 



First Bicuspid 



Second Bicuspid 



Canines 



Second Molars 



8 years. 



9 " 



10 " 



11 



12 to 12J 

 12 to 14 



The following are the results of the application of this test, in a large number 

 of cases examined by Mr. Saunders. Of 708 Children of nine years old, 530 

 would have been pronounced by it to be near the completion of their ninth year ; 

 having the central, and either three or four lateral, incisors fully developed. 

 Out of the remaining 178, it would have indicated that 126 were 8J years old, 

 as they presented one or two of the lateral Incisors ; and the 52 others would 

 have been pronounced 8 years old, all having three or four of the central Incisors. 

 So that the extreme deviation is only 12 months ; and this in the inconsiderable 

 proportion (when compared with the results obtained by other means) of 52 in 

 708, or 7i per cent. Again, out of 338 children of 13 years of age, 294 might 

 have been pronounced with confidence to be of that age, having the Canines, 

 Bicuspid, and second Molars, either entirely developed, or with only the deficiency 

 of one or two of either class. Of the 44 others, 36 would have been considered 

 as in their 13th year, having one of the posterior Molars developed ; and 8 as 

 near the completion of the 12th, having two of the Canines, and one or two of 

 the second Bicuspid. In all these instances, the error is on the favorable side 

 that is, on the side on which it is calculated to prevent injury to the objects 

 of the inquiry ; in no instance did this test cause a Child to be estimated as older 

 or more fit for labor than it really was. 1 



1 The value of this test, as compared with that of Height, is manifested by a striking 

 example adduced by Mr. Saunders. The height of one lad, J. J., aged 8 years and 4 



