Twin births and twins from a hereditary point of view / by Gunnar Dahlberg.

  • Dahlberg, Gunnar, 1893-1956.
Date:
1926
Catalogue details

Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: Twin births and twins from a hereditary point of view / by Gunnar Dahlberg. Source: Wellcome Collection.

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    16 terial in monozygotic and dizygotic of the same sex, we get the figure 26.3 % monozygotic. (With the differential method 26.2 %.) S chápiro, 1912, among 159 twin births finds 22.64 % monozygotic. R a b i n о w i t s с h, 1913, gets 19.7 % monozygotic in 168 pairs of twins. Hans Meyer, 1914, disputes Weinberg's differential me¬ thod. Without further substantiating his views, he says, that the premises of the method are improbable and improved. From the journals of the Charité Meyer has extracted a ma¬ terial from the years 1904—11. On 18,143 single births there occurred 308 twin births, i.e. one to 58.9 single births. Among the twin births are 39 monozygotic, 213 dizygotic, and 56 same- sexed of unknown number of ova. The monozygotic are as 1: 5 in relation to the dizygotic, if the 56 of the same-sexed with undetermined membranes are left out. If (as Meyer suggests) the unexamined 56 are equally divided between monozygotic and dizygotic, the percentage of monozygotic in the whole of the material would be 21.8. Such a division should be com¬ paratively correct, as the opposite-sexed dizygotic have already been sorted out from those of undertermined number of ova, and consequently in the remainder there must be a compara¬ tively great number of monozygotic twins. By the differential rule the percentage of monozygotic works out at 20.1, which must be said to tally quite well. Meyer, however, does not make this comparison with the differential rule. He shows, on the other hand, that among the certain dizygotic, 57.74 % are opposite-sexed and 42.31 same-sexed. This he considers to be contradictory to Weinberg's method, which reckons with 50 % of opposite-sexed. Meyer, however, does not count the 56 pairs not examined, and these, as has been pointed out, should balance the difference. H u s t, 1916, in 94 pairs has 31.8 % monozygotic. W e h e f r i t z, 1925, controls Weinberg's differential me¬ thod with material brought together from literature and finds rather good accordance. This accordance, however, would certainly have been better still, if Wehefritz had employed only