The Author has examined the published statistics of multiple births in England and Wales 1938-45, in Italy 1948-49 and in New York 1936-37, to see to what extent the apparent increase in frequency of twin births as parity increases amongst mothers of a quinquennial age-group is exaggerated by the mere fact of grouping. He concludes that the effect of the 5 year grouping on the rates is small, and that the data from the three countries indicate that at certain ages the probability that a birth will be multiple tends to increase with the order of the birth.

Other than a specific case of concordant Vitiligo in MZ twins, the development of which has been followed for more than 11 years up to now, MZ twins suffering from Vitiligo have been described only three times. In all the four cases, three were concordant, one discordant; this last was accompanied by a discordant disorder of basal metabolism, by hyperhydrosis and exophtalmus. The greater degree of concordance found up to the present day, notably contrasts with the relative extreme rarity of familiar Vitiligo.

I. The results are reported of Rh—Antigens examinations on 61 families with together 154 children and on 423 mother—child relations. No deviations from the theory of inheritance concerning the Rh-Caracteristics could be noticed.

II. The results obtained by examination of 2472 persons concerning the distribution of the Rh-types C, c, D and E in the German population makes it possible to obtain safe conclusions concerning the Rh-type representative for us and its use to the forensic paternity exclusion by calculating the application of the type (acc. to Hirszfeld). There is a far-reaching correspondence between our observations and Anglo-American (Wiener and Race), and Norvegian reports (Hartmann and his staff), about the distribution of the types.

III. A survey of paternity exclusions as observed from our material substantiates the theoretic conclusions and shows also in practice the importance of the RH-Antigens of certain characters (C, c, D and E) for the forensic medicine.

The A. explains the case of a pair of male twins five month aged, contemporaneously and suddenly died of a cardiac insufficiency from hyperthymism.

The examination of both their parents permitted to assure a syphilitic inherited lemish in their children.

Considering the question from the medico-legal standpoint, he does not justify any suspicion of a criminal action when the event may be justificable under the acquaintance of gemellology.

He confirms, besides, reflecting upon the genealogic factors of the parent's families, the theory of Gedda on the hereditary mechanism of gemellogenesis which in the above mentioned case declares itself as an heredity jointed to the sex.

A sample of 583 twins, delivered in two English hospitals, and divided into groups of like sex and unlike sex, has been analysed as regards distributions, means and standard deviations of mother's age, order of birth, birth weight and length of gestation time.

In birth weight the unlike sex have greater means than the like sex, from which it may be deduced that dizygotic twins are heavier at birth than monozygotic.

The correlation of birth weight in twins is 0.727 for like and 0.676 for unlike sex.

Length of gestation time has a correlation with birth weight of 0.345 for like and 0.403 for unlike sex.

Neonatal mortality (including stillbirths) is high for twins, being 16.6% as compared with 4.5 % in single births. When these rates are sub-divided into groups of birthweight, it is found that the rates for the very low weight groups are a little better for twins than for single births, but those round the mean and above it are about 3 times those for single births of average or above average weight.

The mortality rates are a little lower for twins of unlike sex.

1. Data are presented relative to twin pregnancies within the total, the “white” and the “colored” populations of the United States for the 15 year interval from 1922 to 1936, inclusive.

2. Attention is called to the fact that twin pregnancy frequencies in all human populations fall within rather narrow limits, and it is suggested that this fact supports the conclusion based on other lines of evidence that human twinning has some genetic basis.

3. It is shown that the twin pregnancy frequency for the “colored” population is significantly higher than is the corresponding percentage for the “white”. It is concluded that this difference is due, in part at least, to a difference in heredity.

4. It ise stimated that 33.43 percent of all twin pregnancies within the total population are of the monozygotic type and that within the “white” and the “colored” populations considered separately the corresponding percentages are 34.16 and 28.91, respectively.

5. Calculations show that the higher percentage of twin pregnancy frequency within the “colored” population than within the “white” is exclusively the result of a higher percentage of the dizygotic type of pregnancy.

6. It is shown that livebirths among twins have a significantly lower percentage of males than do livebirths among members of single pregnancies. This is attributed primarily to a higher percentage of male deaths in twin than in single pregnancies during early uterine stages.

7. It is shown that the percentage of stillbirth for twin pregnancies is twice as high as is the percentage for members of single pregnancies. Even so it is suggested that there may be at present or in the future a trend started in the direction of an increase in the percentage of plural births within the human species.

8. It is shown that the percentage of sets of twins in which both members are stillborn is higher than the one expected on the assumption that the deaths of the two members are independent events.

9. The percentage of sets of twins in which both members are stillborn is found to be significantly higher for same sex sets than for opposite sex sets. This is attributed primarily to the inclusion of monozygotic sets among the former.

10. It is also shown that the percentage of sets of twins in which only one member is stillborn is significantly higher for same sex sets than for opposite sex sets. This is attributed primarily to the inclusion among the former of monozygotic sets in which one member is handicapped as a result of an unequal twinning process or of some related phenomenon.

11. Many additional differences relative to twin pregnacies are shown in the accompanying tables, but are not discussed either because they are relatively insignificant or because they require supporting data.

In a pair of 14 year old DZ twins of different sexes, a particularly profound emotional separation becomes manifest during childhood.

The twins come from a family whose members are considerably introvert, and where very few exchanges of emotional manifestations take place. The male twin offers a more fundamental alteration of personality, and his emotional control is often overwhelmed by antisocial tendencies of relative frequency. In accordance with her family surroundings his twin, instead, possesses a particularly rigid and severe moral conscience.

The twins are spiritually separated when at the age of eight and nine years, the boy attempts certain sexual approaches on the little girl. At first the child consents, but gradually a most intense feeling of guilt rises up in her, which is accompanied by an aversion, rapidly changing into invincibile hatred towards her brother, whom she fears will subject her to further sexual practises.

Notwithstanding the preponderance of the sexual factor, the antisocial behaviour of the boy, also contributed to a certain extent to this separation.

From a psychoanalytic point of view, the girl's behaviour, characterised by a typical inversion of feelings could be in- terpreted as a reaction formation.

As the boy has been classified from a psychiatric diagnosis as bearing a psychopathic personality which occupies a position between neurosis and psychosis, the eventual possibility of a certain degree of familiar and social adjustement is not to be excluded.

Report of 4 families with two or three sibblings who suffered from different malformations of skeleton system and dwarfism.

In the first family is supposed, that the different severe chondrodysplasie of three children who descended from healthy parents was caused by a recessive gen which is unstable in manifestation.

In the second family was found that a dwarfic mother had two sons with phenotypical differences on chondrodysplasie.

In the third family a sister who was less deformed and a brother with severe dwarfism (among 13 sibblings) showed different phenotypes of a rare (skeleton) system sickness in any way related to chondrodysplasie. Consanguinity of their parents seems to be expression of a single recessive gen.

In the fourth family were found two brothers who had healthy, blood related parents. The abnormities of their skeleton system are supposed to be a rare form of dysostotic dwarfism.

The observations above communicated may show how many special gens exist in pathological human genetics. The phenotypical differences of special human deformities seem to prove a dependence from a respective genotypical association.