Monozygotic bovine quadruplets
H. P. DONALD, W. S. BIGGAR and D. M. LOGAN Animal Breeding and Genetics Research Organisation, Edinburgh Received Io.v.5o ON the 27th January 1949, a Friesian type cow called Peggy, and belonging to Mr William Youngs of Sankence Farm, Aylsham, Norfolk, produced four bull calves. After undergoing considerable publicity for a few days, Peggy died, but the calves survived and were purchased by the Agricultural Research Council, and transferred to the Cattle Breeding Research Farm at Cold Norton in Staffordshire. These calves are remarkable, not only because quadruplets are unusual in cattle, but also because they were born alive, and were all of the same sex. Furthermore, they appear to be the first recorded set judged to be of monozygotic origin. A somewhat detailed account of them, therefore, appears desirable. Unfortunately, two of the calves died a few weeks after purchase, so that a comparison of late developing features became impossible. The evidence on which the diagnosis of one-egg origin is based is as follows. Except where otherwise noted, all remarks apply equally to all four calves.
Causes of variation in the frequency of monozygous and dizygous twinning in various breeds of cattle.
A statistical investigation has been made comprising 12 European cattle breeds with a total of about 5.3 milj. calvings and 120,000 twin births. Season of conception has a marked influence on the frequency of twin births, one maximum corresponding to spring and another one to autumn conceptions. There are significant breed differences in the relation between age of the cows, measured in parities, and the frequency of monozygous (MZ) as well as dizygous (DZ) twin births. On an average, the DZ frequency increases more than the MZ frequency from the first to the fourth-fifth calving; then the age-curves show a plateauing tendency. After the first twin birth, the twinning frequency at the following calvings is 4–5 times higher than in the general population. Apparently, twinning depends on polygenic inheritance and also on various environmental influences, with a threshold for the phenotypic manifestation. It may be assumed that the underlying liability of the cows in a population to bear twins has an approximately normal distribution. The heritability of twinning has been estimated on the binomial p-scale as well as on the x-scale of the normal curve. On the p-scale the heritability of twinning was found to be about 0.02 which corresponds to 0.16 on the x-scale, although with some differences between breeds.
Mathematical Time and Physical Time in the Theory Of Relativity
In the Theory of Relativity time is an imaginary quantity that can not be observed; it is a multiplication of a number that indicates duration of material change and number i that is an imaginary number. i on the square is -1. Time i⁄t is a mathematical time that describes the speed and the duration of material change. In the Universe one can observe physical time only as a stream of material change. It is not that change run in physical time, change itself is physical time.. Distinction between imaginary mathematical time and visible physical time opens some new perspectives into interpretation of Theory of Relativity. c