After World War II, science and especially the biomedical sciences are expanding at an impressive pace and on an ever expanding institutional and economic scale. The number of scientists increases rapidly, and the costs of equipments and laboratory materials increased rapidly. The era of romantic science is over and the ideals of scientific research changed from the individual linked to individual dreams and projects to a full-scale collective effort.

The Stazione Zoologica remains a reference at the international level, and 'the Neapolitan experience' continues to be considered a necessary step for brilliant scientists. This is especially true for Italian biology and for the University of Naples; the Stazione Zoologica for many of Italian researchers is the way to get in contact with advanced biological research, thanks to the presence in Naples of visiting researchers and an extraordinary library. The international character of the institution is maintained thanks to several scientific collaborations, first of all with the Marine Biological Laboratory in Woods Hole Marine Biology and the British marine biology laboratories.

However, the ‘tables system’ produced inevitable fragmentation of research programs and an expensive dispersal of experimental apparatus, since each researcher comes with its own project and tries in Naples to get the best conditions to realize it. This produces a large diversity of research programs, which depend on the scientists who occupy the various tables provided by their governments, with no continuity that could amortize the major investments made necessary by the new type of biological research. Some heterogeneity existed previously, but it increases again after World War II, following the multiplication of the lines of biology research, which is becoming the world's leading science. This produces a hard financial crisis.

It becomes clear that the Stazione Zoologica needs a new administrative and institutional structure, to ensure a solid  financial and permanent basis. For almost a century the Italian government had continued to recognize the unique character of the Stazione Zoologica, a private institution in an international context. But in the new science context, this situation is not sustainable anymore. In 1967 the Italian government entrusted the management of the Institute to a ‘Commissario Straordinario’.

When Italy entered into the First World War, Reinhard Dohrn, son of Anton and at the time Director of the Station, and the German assistants had to leave the country. The station, as private entity belonging to a German citizen, was placed under national control. In 1916 the station was solemnly inaugurated as an 'Italian Institute' and placed under the direction of a national committee.

At the end of the war, after a period of uncertainty, Benedetto Croce, then Minister of Education, in a speech to the Senate on December 9, 1920, suggested placing the Zoological Station again under the responsibility of the Dohrn family, the only way, according to the Neapolitan philosopher, to guarantee the institution its scientific links and its functionality. In October of 1923 its legal status was redefined and the Stazione Zoologica became an 'Ente Morale' (a semi-private institution), under the surveillance of the Ministry of Public Instruction and directed by a Board of Directors, chaired by the Mayor of Naples. Reinhard Dohrn was nominated ‘managing director and administrator’.
The new institutional structure maintains the international status of the Stazione Zoologica, fostering contacts among researchers of different countries and encouraging their presence in Naples, thanks to a total freedom of research and a technical structure effective, able to create ideal working conditions and providing all the research material needed.
The scientific activities of the Stazione Zoologica in the interwar period show a great continuity with the previous period. Systematics remains a priority. The physiology of the embryo, the regeneration, research of biochemical components in marine organisms and their quantitative changes during embryonic development, the study of embryonic gradients, research on bioluminescence and photogenesis, hereditary symbiosis continue to be points of aggregation, while the wealth of the Gulf of Naples, with its flora and diversity of animals both superficial and abyssal forms, favored the development of a new ecological approach, centered on alimentary chains, the complex of organisms, in connection with the biological and physical-chemical environment. And, as in previous periods, the Stazione Zoologica is the ideal place for experimentation of new technologies applied to research, such as the use of cinema for the study of experimental embryology, the first experience of scientific cinematography (Istituto Luce) and research supported by Kodak on gels of animal origin for film.
Once again, however, the main thrust to scientific innovation comes from embryology. The turning point in this kind of research can be identified in a classic article of 1924 in which Hans Spemann and Hilde Mangold had begun to study the morphogenetic processes leading to the formation of the eye in amphibians. This research program is developed further in the following years, through a very complex series of experiments in tissue transplants, many of which are made in Naples, where Spemann worked quite often, accompanied by a substantial group of assistants.

In the 20s and 30s the physiological and biochemical research continues to play a major role in the scientific life of the Stazione Zoologica. Albrecht Kossel and the Svedberg, founders of nucleic acid chemistry, work equally to the Zoological Station, as Jean Brachet, that at this time develops the cytochemical techniques for localization of nucleic acids into cells and embryo. Otto Meyerhoff (a future Nobel laureate) studying muscle metabolism, focusing interest on chemical stimulation of the muscle fiber. In 1935, Zénon-Marcel Bacq and Francesco Paolo Mazza demonstrate the presence of acetylcholine in the ganglia of the optical octopus (Octopus), and identify the substance chemically. The contribution of Bacq and Mazza is a milestone in the history of chemistry of nerve transmission, the first direct proof of its existence in the nervous tissues. Bacq, a pharmacologist from Belgium, in collaboration with Francesco Ghiretti employed cephalopods to develop endocrinology, using adrenaline-like agents.

The Zoological favored another important progress in neurobiology, the discovery of Ernst Scharrer of the phenomenon of what has become known "neurosecretion," the elaboration and secretion of hormones from by nerve cells.

What may be called the modern era of research on cephalopod research begun in Naples with the research of Enrico Sereni, who conducted major experiments on the chromatophores and salivary hormonal secretion. Sereni also works on the peripheral nervous system of cephalopods, in collaboration with the young British researcher John Z. Young, who founded another line of research, that will become characteristic of the Stazione Zoologica, pursued for decades and almost uninterrupted. Working with Sereni on the Octopus, Young discovered by chance the giant axon this became a fundamental tool in exploring nerve conduction. The sections of the brain and giant fibers of octopus and cuttlefish, created by Young at the Stazione Zoologica in 1936 showed the possibility of studying higher nervous activities, such as learning and memory.

The Stazione Zoologica remains virtually closed between 1943 and 1945, with a very small number of researchers and technicians. The Aquarium reopened to the allied troops in December 1943. The Villa Comunale was left by Allied troops on May 1, 1944 and the activity of the station can begin again. The Library was relocated to its place at the end of 1944. After the liberation of Rome, June 4, 1944, contacts are established with the Ministry of Education and the National Research Council, who supported the station consistently. This will create a "Center for Biological Studies", under the direction of Joseph Reverberi, whose main purpose is to create training grants for young biologists. After 1950, the National Science Foundation, newly created, the Lilly Endowment and the Rockefeller Foundation increase considerably their engagement with the Stazione Zoologica. The scientific prestige of the Stazione Zoologica and its location in the postwar period made it rapidly a privileged place for the realization of conferences and scientific meetings. This was also an opportunity for Italian scientists to enter the international circuit. The station hosts important conferences on embryology and genetics, mutagenesis, on neurosecretion. In 1951 the Stazione Zoologica held a conference on the application of X-rays to the study of biological problems, in particular the study of the submicroscopic structure of protoplasm. In this conference, Wilkins shows a figure of X-ray diffraction of the crystalline DNA and this stimulates JD Watson, who attended the meeting, to start its work on nucleic acids, that will take him with Francis Crick's discovery of the double helix.

The phrase 'developmental biology' became popular in the late 1950s, when embryology was in a transition phase and the focus shifts from the chemical organizers to subcellular and cell-cell interactions, the exchange of 'information' between nucleus and cytoplasm and the genetic control of morphogenesis. New developments in molecular biology, especially after the proposal by François Jacob and Jacques Monod of the molecular model of regulation of gene expression, based on repression and induction, suggesting new interpretations of development as a process control in time of expression of a predetermined program in the fertilized egg. The new generation of biologists who work at the Zoological Station in the 50s and 60s century compares well with new problems and new experimental procedures. A. Tyler, T. Hultin and A. Monroy, showed that the control of the genetic program seems, at least in part, already predetermined in the non-fertilized egg, as the ribosomes on which is held the protein synthesis accumulating during oogenesis, but the expression of the messengers contained in them is blocked by particular proteins, which are then eliminated during the different phases of embryonic development. This allowed to integrate in the new historical context some observations made by J. Runnström always in Naples and SO Hörstadius, which had shown that the activation of the egg at fertilization produces the appearance of proteolytic enzymes.

After the pioneering work of Otto Loewi (Nobel Prize in 1936) that had shown that synaptic transmission was mediated by acetylcholine, Bernard Katz and Richard Miledi from the University College in London came to the Stazione Zoologica to study the relationship between calcium and release of neurotransmitters at synapses. Their experiments become classics: thanks to the use of microelectrodes the two researchers discovered the so-called 'membrane potential', showing that acetylcholine is released into 'packets' in very small quantities when the synapse is at rest, while when the termination synaptic is stimulated also increases the emission of a million times. The octopus, Octopus, turns out to be once again a unique material for studying the mechanisms of learning and memory, thanks to the inexhaustible availability of animals in Naples throughout the year. The Posillipo fishermen were able to carry up to 20 or more Octopus in excellent condition, and the station provides specially created tanks, built in a suitable space thanks to the financing of the British Science Research Council. This made possible to create a vast Zoological Station 'cephalopods facility', consisting of more than two hundred tanks in which as many Octopus can be maintained and observed individually.


Along with several collaborators, especially Bryan Boycott, Martin Wells and John Messenger, Young mapped the neural circuits of the brain and of the Octopus through ingenious experiments he explored the learning ability of these animals, and offers new interpretations of the neural mechanisms underlying memory.

From the very beginning, botanical research had been an important component of the scientific life of the Stazione Zoologica. The first guests of the institute were of German researchers who studied marine plants, in terms of ecological and systematic basis for later physiological, cytological, biochemical and cycles of life research. After an initial period as a member of the Department of Botany, since 1912, Georg Funk realized several periods of research in Naples, producing three major publications on the algae in the Mediterranean and giving the botanical research in Naples continuity which extended into the late '50s. The lasting impact of this type of study has been the contribution of an ecological dimension, from which other studies grew and found support. The monographs of Funk (1927, 1955) with the detailed description of the associations of algae, their distribution, reproductive cycles remain the benchmark for algae research in the Mediterranean. Moreover, the observations of Funk have served as a basis for the quantitative study of the changes produced in the ecosystem of the Gulf of Naples from urban and industrial development, which mainly affects the waters coastal waters.

In the early 50's botanical studies take up a great momentum, with new programs of ecological study of the distribution of algae, their cultivation, and especially with the research on various aspects of the life cycle and biochemical functions of Acetabularia.

With an even greater emphasis on Ecology, Botany in the decade 1960-70 begins to discuss new scientific questions relating marine environment. The Benthic Ecology and Biological Oceanography laboratories were established to develop ecological studies in the broad sense, including research on the chemical-physical factors as well as plant and animal communities, in particular benthic ecosystems.

The Stazione Zoologica did not have an in-house research program, apart from Anton Dohrn’s own project, and therefore its structure reflected the major interests of the visiting scientists. However, Dohrn recognized the significance of different sections of science, and the way in which they interact and complement each other. In such a way he was able to create a structure perfectly in tune with the main scientific issues of the time and to bring the best researchers to Naples. Embryology, Comparative Anatomy, Systematic Botany and Zoology, including natural history, ecology and the study of behavior, were the main fields of research in the early decades of the Stazione Zoologica’s activity.
Founded in an era when morphological studies predominated, paradoxically the Zoological Station in 1880 becomes a stronghold of the revolt against Haeckelian phylogenetic embryology. The new generation of biologists is placed in an extremely critical attitude towards the morphological tradition and supports the implementation of a new experimental method to the problems of development, thus giving rise to a new era in the study of embryonic development. The different stages of embryonic development are not observed to obtain the evidence in favor of the phylogenetic inferences, these are not a tool of explanation but become themselves processes to explain, by identifying their causes. Experimental addresses make their way into other areas, such as the study of the cell, the theory of inheritance, the same theory of evolution. The function replaces the objective form of scientific inquiry as an explanatory principle. An object of study, a marine animal of course, is particularly suitable for this experimental research, the sea urchin. With this new tool and new experimental methodology the famous “injury experiment” was conducted in 1888. With a thin needle, Wilheim Roux destroys the nucleus of one of the two cells formed after the first segmentation of the zygote: the undamaged embryo continued its normal development of producing 'half an embryo', demonstrating that cell division is qualitative and each of the primary cells has a predetermined fate, independent from the presence of other cells and from the later stages of development.

Some years after Jacques Loeb realized in Naples artificial insemination, showing that the sea urchin egg can start development when exposed to an acid or to an increase in osmotic pressure. This experimental ' chemical parthenogenesis ' has a great impact on the scientific community and public opinion. Someone even suggested that women should avoid swimming in the sea, because of the risk of chemical parthenogenesis.

In 1889 the German biologist Theodor Boveri began his experiments in Naples on 'hybridisation' of different species of sea urchin, in order to determine whether the core, the protoplasm or both determine inheritance and development. Boveri demonstrates the dominant role of the nucleus in heredity and genetic diversity of the chromosomes, establishing a link with the Mendelian theory, which had just been rediscovered and proposing an initial 'chromosome theory of heredity’.

Between 1908 and 1914, Otto Warburg spent several periods at the Stazione Zoologica, where he carried out his first independent research on the oxygen consumption by the urchin egg after fertilization. In 1909 he discovered that iron is essential for the development of the larval state, thus beginning a new research program on cellular breathing, research that later won him the 1931 Nobel Prize for his discovery of the cytochrome oxydase.

Between 1866 and 1945 Thomas Hunt Morgan works at the Stazione Zoologica before turning to genetics and create the 'Drosophila Group ', giving rise to the chromosome theory of inheritance.

Nel 1889 il biologo tedesco Theodor Boveri inizia a Napoli i suoi esperimenti di "ibridazione" fra specie diverse di riccio di mare, allo scopo di stabilire se è il nucleo, il protoplasma o entrambi a determinare l'eredità e lo sviluppo. Boveri dimostra il ruolo dominante del nucleo nella trasmissione ereditaria e la diversità genetica dei cromosomi, stabilendo un legame con la teoria mendeliana, che era stata appena riscoperta e proponendo una prima "teoria cromosomica dell'eredità".

Fra il 1908 e il 1914, Otto Warburg trascorre diversi periodi alla Stazione, dove realizza la sua prima ricerca indipendente sul consumo di ossigeno da parte dell'uovo di riccio dopo la fecondazione. Nel 1909 egli scopre che il ferro è essenziale per lo sviluppo dello stato larvale, iniziando così un nuovo programma di ricerca sulla respirazione, che gli varrà il premio Nobel nel 1931 per la scoperta della citocromoossidasi.
Tra il 1866 e il 1945 Thomas Hunt Morgan lavora alla Stazione prima di dedicarsi alla genetica e creare il "Gruppo della Drosophila", dando origine alla teoria cromosomica dell'eredità.