188 ON THE ELEMENTARY PARTS OF THE HUMAN FABRIC. 



With this understanding, the results of the application of the following table will probably 

 be very near the truth. 



Central Incisors developed at .... 8 years. 



Lateral Incisors . . . . . . 9 



First Bicuspid . . . . . .10 



Second Bicuspid . . . . . .11 



Canines 12 to 12J 



Second Molars 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 pro- 

 nounced 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 in- 

 dicated that 126 were 8^ 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 incon- 

 siderable proportion (when compared with the results obtained by other means) of 52 in 708, 

 or 7| per cent. Again, out of 338 children of 13 years of age, 294 might have been pro- 

 nounced 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 favourable 

 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 

 labour than it really was. 



m. The value of this test, as compared with that of Height, is manifested by a striking ex- 

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

 was 4 feet and of an inch ; that of another boy, aged 8 years and 7 months, was only 3 

 feet 7 inches. According to the standard of height adopted by the Factory Commissioners 

 (namely, 3 feet 10 inches), the taller lad would have been judged fit for labour, whilst the 

 shorter would have been rejected. The Dentition of the latter, however, was further ad- 

 vanced than that of the former; for be had two of the Lateral Incisors, whilst the former 

 had only the Central ; and the determination of their relative physical powers, which would 

 have been thus formed, would have been in complete accordance with the truth. The elder 

 boy, though shorter than the other by 5^ inches, possessed a much greater degree both of 

 corporeal and mental energy, and his pulse was strong and regular ; whilst that of the 

 younger lad, who was evidently growing too fast, was small and frequent. An instance 

 even more striking has come under the Author's own observation. 



10. Simple Tubular Tissues. 



218. We have seen that all the Animal Tissues, whose structure has been 

 yet considered, derive the materials of their growth and renovation from the 

 nutrient fluid ; which is brought into a more or less close relation with their 

 elementary parts, by means of Capillary blood-vessels. These seem to have 

 a claim to be regarded as among the elementary parts of the fabric; since they 

 are formed quite independently of the larger trunks, and have little in common 

 with them in their function. All those changes which take place between 

 the blood and the surrounding parts, whether ministering to the functions of 

 Nutrition, Secretion, or Respiration, occur during its movement through the 

 Capillary vessels: and the function of the larger trunks is merely to bring to 

 them a constant supply of fresh blood, regulated according to the demand 

 created by the actions to which it is subservient; and to remove the fluid 

 which has circulated through them. When we examine into the structure of 

 the Circulating apparatus in Plants and in the lower Animals, we rind that 

 the canals, which convey the nutritive fluid, are of two kinds ; either simple 

 excavations in the solid tissues or unfilled vacuities ; or tubes with definite 

 membranous walls. The former are known, in Plants, under the name of 

 inter-cellular passages ; and, among the lower tribes in particular, they have 

 a large share in the conveyance of the nutritious fluid from one part of the 



