44 RELATIVE WEIGHT AND VOLUME OF COMPONENT PARTS OF FETAL BRAIN. 



(&) The tabulation of the brain-weights and measurements obtained from 

 large series of cases, including material of various races and ages and representing 

 both sexes (Boyd, 1861; Donaldson, 1895; Ziehen, 1899, 1903; Vierordt, 1893). 



(c) Statistical studies in which these tables are used to determine the correla- 

 tions existing between brain-size and age, brain-size and intellect, and the compar- 

 ison of brain, body, and intellect in the two sexes at various ages and in different 

 races, as has been so ably done by Pearl (1905a, 19056) who, in addition to the above 

 material, used the tables reported by Bischoff (1880), G. Retzius (1900), Marchand 

 (1902), Matiegka (1903), and Boyd-Marshall, all as reported by Donaldson (1895). 

 The employment of such biometric methods gives results of great value to the 

 investigator, since it enables him to make a great number of comparisons and to 

 tabulate and express his results with a clarity and an exactness not possible by any 

 other method. 



(d) This last class would embrace the relatively limited number of observa- 

 tions dealing with material sufficiently young to come within the scope of the 

 present paper, and includes extracts from Major Boyd's (1861) monumental work 

 on approximately 2,600 cases autopsied at Marleybone Workhouse and the Somerset 

 Lunatic Asylum. These cases were grouped, according to age, into 18 periods, the 

 first 3 of which are of value in this connection. They comprise 48 premature still- 

 born, 83 term still-born, and 90 new-born infants. The various measurements as 

 given by Boyd were the total body-length from the vertex to the inner side of foot 

 behind the ball of the great toe, and the following head measurements : circumference 

 around the occipital protuberance to the space behind the eyebrows; transverse, 

 from the opening of one ear, over the vertex to the opening of the other. Doubtless 

 the method of subdividing the encephalon employed by Boyd was, as assumed by 

 Donaldson, for the purpose of making the cerebrum one unit, the cerebellum one 

 unit, and the medulla, pons, and midbrain one unit; though it is probable that a 

 part, at least, of the mesencephalon was included with the cerebrum, since, upon 

 removing the calvarium and dura, Boyd "removed the right and left hemispheres 

 of the cerebrum in slices to the tentorium." The cerebellum was isolated by cutting 

 the crura close to the pons. 



A closer study of the group of specimens tabulated as premature still-born, 

 which are recorded as measuring 10 to 18 inches total length (CH), or approximately 

 250 to 460 mm., shows that they would correspond to an age range from the end of 

 the fifth to the end of the eighth month, according to Strata's tables as reported by 

 Martin (1914). According to Mall (1910), these two extremes would for the 

 younger correspond to a sitting-height (CR) of 167 mm., age 20 weeks; and for the 

 older a sitting-height of 310 mm., age 35 weeks. The weights of the brain parts in 

 these two extremes would be in the smaller fetus 41.25 grams for the cerebrum, 1.98 

 grams for the cerebellum, and 1.32 grams for the medulla-pons; and in the larger 

 fetus 297 grams for the cerebrum, 24.75 grams for the cerebellum, and 1.65 for the 

 medulla-pons. These figures must at best be accepted with reservations, since 

 the tables from which they are taken are undoubtedly inaccurate in some particulars. 

 For example, the weight of the encephalon in no case equals the added weights of 



