In this first report the Authors take into consideration only the meaning of group I of Arneth's formula, utilizing the data of the zoo findings on pairs of DZ, of healthy MZ and diseased MZ Twins. They find, in group I, a moderate influence of the disease factor.

These findings are believed to be in agreement with Pappenheim's theory, according to which the relationship between the first group of Arneth's formula and the following groups would be lined more closely to a maturative factor influenced by physiopathological conditions than to a cellular constitutional, which is present, though.

The genie factor dominate instead in the other four groups, as will be amply shown in the next report.

Report about some observations with special concordance in 4 pairs of identical twins with kidney-stones, one pair of especialy concordant allergies, hyperthyreosis and cystical-glandular hyperplastic uterus and a pair of identical twin sisters, on-concordant congenital dislocation of the hip, resistant to all therapeutic essays.

The especially concordance of the demonstrated twins is to be explained, that in the cases observed by the author is to suppose a stronger effect of chief gens and a lower manner of modifying by side gens or exogen ly ten years old, with particulary factors than in the ordinary states of twins with corresponding hereditary diseases.

A finally demonstrated pair of non identicaly twin brothers with same deformities of the knees and same clinical symptoms) directs, that beside the same genotypus also the same exposition may realize especially twin concordances.

This study is based on pedigrees of 287 patients with Rheumatic Fever, which are compared with pedigrees of 300 controls: 11,7 per cent of all relatives in the first group had rheumatic fever, compared to 2,2 per cent of all relatives in the control group.

An hereditary predisposition to rheumatic fever is definitevely to be admitted.

This predisposition is due to the presence of a principal autosomal dominant gene with reduced penetrance and variable expressivity.

It seems to have no genetic relationship to the diathesis of allergic diseases and the diathesi of degenerative connective tissue disorders mesenchymotic diathesis.

The Author describes two case of Fanconi's syndrome in a 5-year-old boy and in an 11-year-old girl respectively. A diagnosis was made in both of erythroleucothrombocytofenia and medullary aplasia, cutaneous, hyperpigmentation, some shortened and bent fingers, symptoms of haemorragic diathesis and of alterations in body development with radiological signs of intracranic hypertension, high levels of plasmatic proteins with increased globulins. In the boy scleroedema was also found. The tests for haemorragic diathesis hinted in this case, at the presence of anticoagulants in the blood.

The statistical study of all the cases published in the literature and an appraisel of the results by the methods of Lenz and Hogben induces the admission that Fanconi's syndrome is a hereditary disease transmitted by a recessive character with multiple effects irregularly expressed.

The Author give a detailed description of a rare observation of hypophyseal dwarfism in a monozygous twin.

The patient showed the classic symptoms of dwarfism and infantilism which have produced a discordance in some characters; important and useful are the results obtained from clinical and laboratory data. They have confirmed the diagnosis of zygotism.

The Authors refer the results of a genetical, clinical and statistical research on a group of 265 patients with cancer of the prostate. The data show a significant familiar incidence only for the cancer of the same site.

Wiener's methods for estimating gene frequencies from MNS data are compared with the maximum likelihood methods, and found not to be fully efficient. The extra effort and expense which would result from the use of such methods is discussed. It is concluded also that the number of significant figures advised by Wiener is not sufficient.