The concept and definition of constitutional pathology. Genetic erythropathies such as constitutional spherocytosis, leptocytosis, ovalocytosis and drepanocytosis and their relation to hemolytic clinical syndromes are discussed. Sickle cell trait, sickle cell anemia, and sickle cell disease have to be distinguished as clinical manifestations of drepanocytosis. They represent a special variety of a « status degenerativus » (Bauer). Four genetic types of human hemoglobin have so far been identified that differ from each other by their molecular architecture and chemical reactivity. Several constitutional abnormalities of erythropoiesis other than those just mentioned are discussed: a hereditary defect in hemoglobin synthesis; erythroid multinuclearity; acanthocytosis; Fanconi's syndrome of hypoplasia and abiotrophy of the bone marrow as another variety of a status degenerativus.

Provided the assumptions underlying Weinberg's method of differentiation of types of twin pairs are correct, this analysis of the statistics of twin births in Italy in the two years 1949 and 1950 shows that there are variations in the frequency of monovular twin births greater than can be attributed to chance deviations from a constant frequency of monovular twinning. There is a tendency for the frequency to increase with maternal age, and for young mothers, a tendency for it to increase also with parity. In general, the occurrence of monovular twinning is probably more closely related to maternal age than to parity.

The frequency of binovular twinning appears to be independently related to both maternal age and parity. Amongst births of each rank the frequency of twin births increases to a maximum at maternal ages 35-39 years; and, at each age level, the frequency does not change between birth ranks 1 and 2 but subsequently increases fairly continuously. There is a suggestion that there may be a modal birth rank as well as a modal maternal age, and that binovular twinning may be no more closely related to maternal age than to parity.

Thalassemia, that I propose to call Microkarterocytosis, can be divided into three forms to be distinguished under the names of minima (healthy carriers), minor (Rietti and Greppi's disease), major (Cooley disease).

It can be inferred that Thalassemia is a mutation developped in a mediterranean superior paleolitic race that showed also the character high cheek bones.

In my researches of 1941-42 I for first showed that thalassemia is a dominant hereditary character with homozigotic letal effect (heterozigotes the healthy carriers, homozigotes Cooley' patients).

Heterozigotes throug an increased expression of the morbid gene develop Rietti and Greppi disease, as I inferred in 1949.

The researches on genetics that I carried later on Drepanocytosis have shown a behaviour equal yo that observed in Thalassemia.

In Drepanocytosis the heterozigote condition determines the healty carriers and the less serious cases of sickle cell anemia, the condition of homozigote the most serious form of this anemia.

A morbid form clinically similiar to the slight cases of Cooley disease is detectable in subjects whose parents show separately one the Thalassemia-stigmata and the other the Drepanocytosis-stigmata. For this latter form the name of Thalassodrepanocytosis is suggested.

The presence of drepanocytosis inindividuals of european races can be explained with very ancient crosses with individuals of negro races.

The genetic roots of speech development in children are being investigated. On the basis of observations in the development of speech in 12 monozygotic twin pairs it could be shown that not only the retarded but also the normal development of speech is an idiotypic characteristic. It must be considered however, that we are not dealing with a simple characteristic, but with the result of a whole complex (intelligence, type of immagination, fine-motor and vitality) of the mentioned root. Further examinations regard the disposition for stammering. On the basis of research with monozygotic twins, of which one partner during the examination presented only signs of cluttering, the other one, however, clonic-tonic stammering, while both twins had a pathologic electroencephalogram, the hereditary basis of speech defects and stammering is shown. However, only in half of the cases of monozygotic twins one can find a disposition for dyslalia, which can be of a very different (periphercentral) nature.

Twins deriving from a single zygote were produced in Triton alpestris and Triton taeniatus by two different series of experiments. The first type of experiments proceeded, by means of a glass thread put on and cutting through the median plane of early gastrulae, to a division of these into two lateral (right and left) halves. These halves may give rise to normally formed identical twins (fig. 2), or to twins with more or less accentuated deficiencies on their inner sides (figg. 3 and 4). In extreme cases they may even produce left or right half-embryos, or much reduced malformations with very imperfect organ formation. Generally considered, the regolation in the head region is better than that in the tail one, and much better than in the trunk. Most of the heads show two eyes of equal size and normal position; in rare cases we encounter two eyes of different size, or synophthalmus or cyclopia. The «real» half-embryos have only one laterally situated eye (tab. 2). The normally formed identical twins deriving from half an egg each, develop into properly proportionned embryos of half the normal size; the resulting larvae reach the normal size of the equally-aged control larvae deriving from entire eggs, often before the stage of nourishment, (fig. 5, tab. 3).

In the second series of experiments, an early gastrula was cut through in correspondence to the median plane, and then the complete presumptive epidermis of another gastrula and, respectively, of a third one, was stuck on to the wound surfaces of the halves in normal orientation (fig. 6). The right and the left combinations resulting therefrom give rise, in the original median line, to long, narrow and apparently somewhat too great neural plates, the external half-portion of which was fournished by the host half-gastrula and is somewhat more strongly developped than the inner half-portion deriving from the presumptive epidermis (fig. 7 a, b). This epidermis that was stuck on to the gastrula-halves' surfaces, takes part in the formation of the embryos either totally or at least for its greatest part. No perfect larvae will be formed (tab. 4). The head is always bilaterally developped, but it is often asymmetric and shows synophthalmous or cyclopic character (figg. 8, 9, 10, tab. 5). The trunk is sometimes normal (fig. 8 a), but it may also show an axial system of too great length (fig. 8 b), or dorsal deficiencies—often in the form of either symmetrical or asymmetrical Spina bifida—with dorsal incurvation (fig. 9 a, b). The tail can be either normal, or crooked, or defective, or doubled. In the best cases we see, in the first series of experiments, the regolation of the half-organiser of the gastrula-half into an entire organiser of half the normal size, while, in the second series of experiments, the regolation can produce an approximately normally sized entire organiser, which however, in the anterior head region is lacking of its full indutcive capacity.

In both series of experiments the right hand member of the twins was observed to show inversion of the situs viscerum.

The conclusions they arrive at, is that from the standpoint of the Rotest, the twins (mono-or-dizygotic) present themselves as distinct and original personalities. The predominant rôle played by the peristasis over the constitution is thus emphasized.

Thirty couples of twins (23 mono-and 7 dizygotic) were studied with the Rorschach-test.

Detailed analysis is given especially for the larger groupe of monozygotic twins; the identical responses and the quantitatively identical Ro-factors, being particularly discussed with the help of synoptic tables. In spite of their findings, the authors underline the scarcity and little significance of the identical factors.

In a family 5 females belonging to 3 generations were found with following malformations: Syndactyly (webbed up to the nails), oligodactyly, tendency towards duplication of digits, and brachydactyly. The intrafamiliar variability was not considerable with exception of an probandus having with 5 digits (with duplication on one digit). On the base of ontogeny the question is discussed if the disturbing factor concerning the palm of hand or concerning the squeleton is prevalent. In this family the two dispositions are probably combined. In bibliography a pedrigree with this combination of multiple malformations was not found.