Studies on the variation and correlation of skull measurements in both sexes of mature albino rats (Mus norvegicus var. albus) / by Shinkishi Hatai.

  • Hatai, Shinkishi.
Date:
[1907]
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Licence: In copyright

Credit: Studies on the variation and correlation of skull measurements in both sexes of mature albino rats (Mus norvegicus var. albus) / by Shinkishi Hatai. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    out to be skew (that is a non-linear regression) then the relation should be more complicated and a simple proportion would fail to correctly express the relations existing between the two characters under consid- eration. On the other hand if the regression is linear the relation may sometimes, but not always be shown by a simple proportion just as well as by a characteristic equation. (1) Fronto-occipita) length, cT = 0.6326 Entire skull length, cf + 4.226 (2) Fronto-occipital length. $ = 0.6663 9 - 1.311 (3) Squamosal distance. d = 0.1100 “ (^4-10 616 (4) Squamosal distance. $ = 0.1004 “ $ + 10.884 (3) Height of skull. cf = 0.1634 ** + 4.426 (6) Height of skull. $ = 0.0937 9 -t- 7.246 (7) Length of nasal bone. cf = 0.4911 “ d - 4.286 (8) Length of nasal bone. ? = 0.6619 '• 9 - 7.651 (9) Capacity of cranium. d - 0.2790 •• d — 1.172 (10) Capacity of cranium. 5 = 0.2863 9 - 1.627 (11) Zygomatic width. cf = 0.6243 “ d - 6.269 (12) Zygomatic width. $ = 0.6830 “ 9 - 3.298 (13) (Height X length X width) i, d = 0.2690 “ d + 6.672 (14) (Height X length X width) i, § = 0.2119 “ 9 -f 7.619 (16) Brain-weight, d = (0.0072 Body-weight, d -t- 9.349) -e 6.980 (16) Brain-weight, 5 = (0.0261 fi 9 -t- 6.168) -e 6.009 Conclusions. 1. All the characters here examined are absolutely greater in the male than in the adult female. 2. The coefficients of variation reveal the fact that the male characters show a general trend to a greater degree of variability than those of the female. The length of the nasal bone and the zygomatic width show a much greater variation than any other skull characters in the two sexes. 3. The coefficients of correlation are always positive and tend to be higher in male than in female. The correlation between cranial capacity and body-weight was found to be quite high (0.516 in male and 0.692 in female). 4. The brain-weight corresponding to the observed body-weight may be calculated from the following two characteristic equations: Brain-weight, male = (0.0072 X (body-weight, male) 9.349) -f- 5.980. Brain-weight, female = (0.0251 X (body-weight, female) + 6.168) 6.009. 5. The observed sexual differences are considerably reduced when the length of the entire skull is equated to either the male or female standard. When the lengths of the entire skull in the two sexes are equated and