The Authors have investigated the problem of foetal membranes in monozygotic and dizygotic twin pregnancies. The material consisted of anamnestic information derived from the twin case files of Rome's Mendel Institute.

In a sizable number of twin cases (3, 107) it was possible to establish zygosity and the various frequencies of monochorionic or dichorial single or double placenta.

Statistical analysis of this material shows that the frequency of monozygotic twin pregnancies with one placenta and one chorion is 68.35%, while 31.65% have two placentae and two choria. On the other hand, 83.29% of dizygotic twin pregnancies have two placentae and two choria, while 16.71% have one placenta and one chorion.

These figures exceed the material's margin of error, calculated on the basis of an appropriate index. Some case, diagnosed as bichorial with one placenta, are explained as due to two placentae fused into one piece, causing a mistaken diagnosis at birth.

The deterioration of mental health of our population is usually interpreted as the result of the increased modern life stress in our atomic age with its implications of the « cold war ». It is not a greater cultural life stress, however, but rather a lower individual resistance to it that accounts for the increased frequency of psychoneuroses in modern society. The term « mental retardation » comprises two categories: one is caused by genetic factors or acquired intra-and extrauterine diseases of infancy and childhood, the second is due to functional mental retardation if the normal individual genetic endowment has not developed to its full capacity and has persisted in a state of immaturity without any interference of a disease. The characteristics of such functional mental retardation (psychic infantilism) and their manifestation in society are outlined in detail. Instincts and emotions insufficiently inhibited by intellect determine the behavior of the functionally mentally retarded. Deficient ethics and responsibility are very often consequences of deficient intellect. Conformism is a subterfuge and evasion from personal responsibility. Exuberant imagination and fantasy of an immature mind, uncontroled by intellect, becoming prevalent in a schizoid personality have eliminated the concept of beauty-and this is the essence of aesthetics-from creative art, music and literature. Mental hygiene is chiefly the job of the family home and the teachers in primary and secondary schools. Education is more than drill and training. Teachers cannot be replaced by machines. Automation technics, recently used even for personality assessment, are out of place in this field.

1. We collected 27 pairs of twins (MZ 21, DZ 6) ranging from 41 to 80 years, and 16 pairs of homosexual siblings (SL) ranging from 62 to 90 years, all of whom were Japanese in the western district of Honshū-Island. First, we measured the bodily constitution, certain body parts and certain bones, and investigated their life- histories. Next, we investigated various senescent phenomena. That is: — the approximate number of gray hairs on the head, the appearance and the size of alopecia senilis in the parietal region, the approximate number of wrinkles in the frontal region, the comparative number of sulci cutis on the nape of neck, the back of the right hand, and the anterior chest, the development of senile pigment spots on the face, the back of the right hand, the extensor surface of the right forearm, and the upper half of the back, the appearance of the senile wart, the development of pinguecula, the development of arcus senilis, the development of marginal protuberances on the lumbar vertebral bodies, and the upper end of the tibia, the existence of fabella in the right knee, and the calcification in the wall of the arch of the aorta.

With regard to these items we calculated the middle percentage deviation, the coefficient of correlation, or the rate of concordance, and on the photographs or X-ray photographs the resemblance between both partners was examined.

2. We have concluded that the following items are mainly subject to the control of heredity. That is, the approximate number of gray hairs on the head, the existence, the localization and the shape of alopecia senilis on the parietal region in ♂, the localization and the shape of wrinkles on the frontal region, the localization and the development of senile pigment spots on the face, the development of pinguecula and of arcus senilis of the eye, the development and the shape of marginal protuberances on the lumbar vertebral body, and the development of marginal protuberances on condylus lateralis et medialis of the tibia. On the other hand, the following items were found to be fairly subject to influence of the environmental factors. That is, the appearance of alopecia senilis on the parietal region in ♀, the number of wrinkles on the frontal region, the comparative number of sulci cutis on the nape of neck, the back of the right hand, and the anterior chest, the number of senile pigment spots on the back of the right hand, the extensor surface of the right forearm, and the upper half of the back, the appearance of senile wart on the body, and the calcification in the arch of the aorta.

3. Concerning those senescent phenomena, which are strikingly subject to the control of heredity, a certain degree of difference between both partners of MZ was sometimes recognized. When the differences in the progression of various senescent phenomena between both partners of MZ were observed, it was often recognized that some senescent phenomena make more progress in one partner, while on the other hand the other ones do in another partner.

4. In order to decide certain environmental factors, which have influence upon the difference between both partners of MZ, we referred to the existence of heavy labor for long duration, the number of deliveries, the grade of the sunburn, the habit of alcoholic drinking, smoking, and history of various diseases. However, we could not decide that some of these factors had certain definite relationship with the progression of certain senescent phenomena. However, we might probably presume that the old-styled Japanese hair dressing worn for many years had a certain relationship with the appearance of the baldness in ♀.

In an anatomo-pathologic investigation on 21 twins (9 pairs and a set of triplets) who had died within 26 days from birth, the Authors have found a majority of lesions of the respiratory system (in 5 cases hyalin membrane, in 4 bronchpneumonia, in 10 desquamative alveolitis associated with atelectasia, emphysema, congestion, haemorragiae, ouedema and substances ab ingestis). Interval between cotwin death lies between 15-18 hours in 8 pairs, 12 days in one pair, 15-11 hours in the triplet set. The highest frequency of mortality was between the 11th and the 16th day: 55%, which differs from that for single born prematures and immatures. Qualitative and quantitative concordance of lesions was remarkable in seven pairs.

In one pair of twins, who died within 30 hours of each other, only the type of prevailing exsudate differred (leucocytes in one, monocytes in the other), while the degree of the lesions was similar. In another pair of twins, whose death was due to exsudative respiratory lesions, one, dead on the 2nd day, exhibited the symptoms of hyalin membrane syndrome, and the other, dead on the 14th day, the symptoms of bronchpneumonia. The two members of the triplet sets who died first, were affected by an egual degree of desquamative alveolitis, while the third, who died 11 hours later, by a leukocyte bronchial catarrh. With regard to the collected data, the Authors proceed with some considerations.

After a short introduction on the relationships between ABO blood groups and the main racial groups, the Authors consider the diagrammatic representation of the p, q, r values, according to the method by Streng, and apply it to the frequencies in Italy. Another method of diagrammatic representation, according to C. C. Li, is also considered, and a comparison is made between the two methods, both applied to the frequencies of ethnically similar populations, such as Caucasoids, Corsicans, Sardinians and Basques.

The need is emphasized for more detailed studies, i. e. at the level of regions, countries, so as to provide as many data as possible.

In this work the author by making use of parochial archives in Busnago (Milan) has controlled the long life proceeding of 187 among the 259 twins-pairs numbered during a period of three centuries (1632-1962). The author has verified the mothers' age at the moment of childbirth.

He has been able to point out a greatest concordance in the average life time of the MZ pairs in comparison with the DZ ones, which agrees with the hypothesis of a genetic long life factor. The mothers' average age, studied on a small group of population during a period of three centuries resulted, in the 159 cases the author could peruse, to be from 30 to 35 years, of age in agreement with the data collected by Gedda on the global Italian population during short periods of time.

This average age supports the hypothesis that among the factors of multiple pregnancies may be numbered besides mothers' age a geographic (racial) variability.

The Authors investigated the haptoglobin groups with immunoelectrophoresic technique in 150 subjects from Liguria. It was observed a frequency of the 39,33% for the types Hp1/Hp1 and Hp1/Hp2, of the 21,34% for the type Hp2/Hp2.