774 AMERICAN ANTHROPOLOGIST [». s., i, t
the two races prevails in early youth. Another series of observatk shows that colored children are much more sensitive to heat than vb children.
Unfortunately the method used by Dr Mac Donald in present the results of his statistical inquiries is such that it would be impossi to form an idea as to their value, if the variability of the phenomc discussed were not fairly well known from other sources. He gives his tables the grand totals from which his averages were calculat These are entirely unnecessary, while the variability of each series a the error of the average, which are essential, are not mentioned at As a consequence of this omission a number of the conclusions dra by the author cannot be considered valid. The following seem dou ful : " Children are more sensitive to locality and heat on the skin bef' puberty than after; and those of non-laboring classes more than th< of the laboring classes." Others cannot be considered as prove such are, that dolichocephalism increases with decreasing ability ; tl boys are less sensitive to locality and more sensitive to heat than gii the statements regarding the relation of height, weight, and hei{ sitting of dull and bright boys ; that mixture of nationalities seems be unfavorable to the development of mental ability. It seems to likely that all the conclusions bearing upon the changes of men ability with age are based on the fact that the judgments of the teach as to mental ability at different ages are not comparable. The teach judge by the attitude of children toward their lessons. When th are easily grasped they are considered bright. Therefore, if the autl shows that dulness becomes more frequent with increasing age, I thi he proves that the curriculum of the higher grades is relatively mi difficult than that of the lower grades, but not a peculiarity of men development. The slight differences found in height and weight of d and bright children are important, because they contradict the valid of Dr Porter's results which were obtained by a different method classification, namely, by comparing children of the same age different grades and classing those in advance of the age as brij those who are retarded as dull. This method of classification is oj to the objection of introducing an element of artificial selection i to promotion from grade to grade.
Besides the results of his own studies Dr Mac Donald give summary of observations of others, without any attempt at critici and a list of instruments for anthropometrical and psychological Still! which may be useful to those who have no access to the catalogues the makers.
�� �
