The effect of Chlormadinone on the proliferation of Ehrlich ascites tumour was studied by employing the stathmokinetic method. In a high percentage of female mice carrying the tumour and treated by Chlormadinone an increase in tumour cell proliferation was observed, while in a few animals the proliferative activity was decreased.

No significant changes were observed in tumour cell proliferation in the male mice.

A review of 62 cases of leukemia in twins reveals most cases occurred in MZ twins, although diagnosis of zygosity was at times admittedly questionable. Concordance was clearly highest in MZ twins of the perinatal-congenital period. This tendency was not maintained at later stages of life.

The older concept of a human placental barrier has been greatly modified. Tracer substances have demonstrated that leukemic cells pass the placental barrier. Materno-fetal transmission of leukemia is well known; all forms of murine leukemia can be transmitted similarly from generation to generation. Certain requisites effect the transmission of neoplastic-hematopoietic disease during pregnancy. Rare cases are reported of pregnant women with leukemia who bear children in whom clinical leukemia subsequently develops. The maternal diagnosis was made at the time of, or shortly after, delivery, suggesting an evolution of the maternal disease late in pregnancy.

That both partners of a pair of twins, either MZ or DZ, can become ill with leukemia within days or months of each other, appears more than coincidental. Chromosomal defects, common environmental factors, and conjoined intrauterine circulations may be important in the transmission of leukemia from one twin to another, a theory supported by the frequent concordance during the first year of life.

The relationship between hypodontia and birth weight was investigated in 262 twins from the naval recruit population at Great Lakes. The overall frequency of hypodontia including third molars was 34.8%. Excluding third molars, hypodontia frequency was 11.6%. Anatomic distribution of congenitally missing teeth and frequency of third molar hypodontia were similar to other studies, but hypodontia of teeth other than third molars occurred two-three times as frequently in twins as in the general population.

The frequency of low birth weight (2500 g or less) in the twin sample was 47.7%. Hypodontia occurred more frequently in twins with low birth weight (42.6%) than in twins with birth weights over 2500 g (28.6%). Mean birth weight of twins with hypodontia was 2479 g, and without hypodontia, 2675 g. Twins with missing teeth other than third molars had a mean birth weight of 2357 g.

Mean birth weight was lower and hypodontia frequency was higher in MZ than in DZ twins. Discordances in anatomic location and number of missing teeth occurred in several MZ and DZ twin pairs. Discordances within MZ sets tended to be related to anatomic location rather than number of missing teeth. Six twin pairs (5 MZ and 1 DZ) out of 20 (13 MZ and 7 DZ) having one or more missing teeth had perfect concordance in both number and location of missing teeth. In 28 pairs neither member had hypodontia.

Mean intrapair variance in number of congenitally missing teeth was almost ten times greater in DZ than in MZ pairs, indicating the presence of a strong genetic component in connection with tooth number variability in twins.

Two members of an Italian family are affected with progressive spinal muscular atrophy. One, a male, has had the disease since his early infancy and, though severely disabled, is still living at the age of 13. In his sister, the first symptoms appeared at the age of 15, and the disease seems to be rapidly advancing. Their parents were consanguineous. Their mother, however, married twice, her second marriage being nonconsan-guineous and producing no affected children.

The study of this family and an analysis of the literature led to the following conclusions: (a) early onset of the disease does not necessarily mean that the course will be malignant; (b) the disease usually has a similar onset and course in subjects belonging to the same family.

In many families, however (and these have been examined in the present paper) malignant Werdnig-Hoffmann disease is found to coexist with the Werdnig-Hoffmann disease with a prolonged course, the Wohlfart-Kugelberg-Welander disease with infantile onset, and the Wohlfart-Kugelberg-Welander disease with juvenile onset. We feel, therefore, that from a genetic point of view all these forms should be included into one and the same group.

A reanalysis is made of the data obtained in two surveys in Brazil, regarding the inbreeding load of Whites and Negroes. It is shown that the differences detected are probably spurious, and mainly due to environmental factors. The “total” inbreeding load estimated for the pooled sample showed nonsignificant difference between Whites and Nonwhites.

Hand prints, estimates of degrees of skin pigmentation and percentages of Cherokee ancestry of 700 Indian pupils attending the Cherokee, North Carolina school were analyzed. The pupils are of mixed Cherokee-White origin. The average proportion of Cherokee ancestry is approximately 60%, the percentages being significantly higher in upper than in lower grades.

The frequencies of palmar patterns are similar to those recorded for other North American tribes. Frequencies of patterns in each of three palmar areas show significant associations with degrees of pigmentation, the highest association occurring between light pigmentation and accessory triradii in distal interdigital areas.

Red cell acid phosphatase phenotypes were determined in 517 unrelated persons from Sweden (317 men, 200 women). The observed gene frequencies were pA = 0.372; pB = 0.558; pC = 0.070.

Experiences in 101 cases of disputed paternity with 167 men involved are reported. On grounds of red cell acid phosphatase phenotypes, ig men (in 18 cases) could be excluded.

In all 112 mother-child combinations studied the distributions of phenotypes were in agreement with the genetical hypothesis suggested by Hopkinson et al (1963).

On the basis of the distribution of taste sensitivity to PTC in 50 parents-child(children) family groups, two different hypotheses are suggested for the mode of inheritance of this trait.

Several slide preparation procedures were studied in order to render a semiquantitative indication of an optimum technique or techniques, concerning the over-all cytological quality of the chromosome spreads effected by each technique. A method of scoring for karyotypically analyzable spreads is given. It is concluded that one of the techniques (technique D) be utilized for routine karyotypic studies while a combination of two of the techniques (techniques D and E) should be employed for more extensive studies.

Fifty marriages of twins to twins have been studied. Most of them have the characteristics of MZ twins. All have an identical outcome of their marriages within each set. This finding and others from the literature are consistent with the idea that marital stability depends in part upon one's original “blueprint” for physical and emotional health.

Two findings in this study, and others from the literature, are consistent with the idea that similarities at the chemical level may in general tend to promote a better understanding of each other and hence more congenial relationships: (a) all but one of the twin foursomes have lived closeby; three-quarters of them share the same house, even after they have had children; and (b) there is some degree of similarity in the ABO and Rh blood groups between husbands and wives in this sample.

The stably-married twins knew each other for an average of four years before marriage, whereas the divorced and annulled ones met only a few weeks or months before marriage.