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P Dullemeijer

Publications and source records attributed to P Dullemeijer.

16 recordsLinked to original sources
PubMed1997

The variety of explanations of living forms and structures.

Over the last decades the image of vertebrate morphology has become at some places chaotic and even opportunistic, which seems to be due to the lack of appraisal or recognition of the leading concepts of the field. This paper analyses the changes in morphology, and shows that these changes have enriched research aims and that the discipline has a clear methodological and philosophical coherence. The situation in morphology is analysed from a semi-historical and review-like point of view to see what aspect is aimed at for explanation, and what types of explanation are used. A preliminary conclusion is reached that the animal form still has to be explained, and that the types of explanation for living form and structure can be divided into three main categories: (1) a category of typological explanation: (2) a category of functional explanation, including a specific constructional explanation; and (3) a category of causal explanation. Each of these categories has a static and a dynamic aspect. The dynamic aspect includes an explanation connected to life time (the system dynamic and morphogenetic explanation) and an explanation connected to evolutionary time (the historical explanation). These categories are used for structure at the molecular up to and including the organismic level of organization. The main challenge for the future is to integrate these different categories of form-explanation and determine their relative dominance when a theory of biology, that is of biological form and activity, is developed.

Animals↗
PubMed1987

Induction and deduction in morphology.

Professor de Wilde's scientific contributions can be divided into two separate areas based on the applied methods: induction and deduction. The first method is used in the investigation of the finger ridge pattern and the second in that of the branching of bloodvessels. It is shown that with induction alternative classifications and explanations remain always possible and that the ultimate choice of the classification depends on supposed biological meanings or practical applicability. In the case of the finger ridge patterns the latter criterion is decisive. With the deductive method a sufficient logical explanation within the boundary conditions can be reached. Alternatives can be presented if the boundary conditions are changed or the functional parameters have to be chosen differently, which is necessary when direct observation (induction) "shows" that other functions are involved. A number of advantages and problematic points in both methods are analysed and their relationship and function in morphology are demonstrated in the mentioned research topics.

Anatomy↗
PubMed1982

The feeding apparatus of Caiman crocodilus; a functional-morphological study.

A functional morphological study on the cranio-facial region of Caiman crocodilus was carried out. The anatomy of the skull, mandible, cartilaginous structures and the muscles of the jaw was described. Myography experiments, an X-ray study and observations of behaviour gave insight into the sequence of actions during food-intake. Evidence has been obtained that the cartilago transiliens, attached to the medial side of the mandible, is used to block the jaws relative to each other. For each food-intake action, the amount of material necessary to resist muscle force was calculated. Integration of these figures, together with a consideration on the lines of stress, resulted in a paradigm for the mandible.

Alligators and Crocodiles↗
PubMed1980

Functional morphology and evolutionary biology.

In this study the relationship between functional morpholoy and evolutionary biology is analysed by confronting the main concepts in both disciplines. Rather than only discussing this connection theoretically, the analysis is carried out by introducing important practical and experimental studies, which use aspects from both disciplines. The mentioned investigations are methodologically analysed and the consequences for extensions of the relationship are worked out. It can be shown that both disciplines have a large domain of their own and also share a large common ground. Many disagreements among evolutionary biologists can be reduced to differences in general philosophy (idealism vs. realism), selection of phenomenona (structure vs. function), definition of concepts (natural selection) and the position of the concept theory as an explaining factor (neutralists vs selectionist, random variation, determinate selection, etc.). The significance of functional morphology for evolutionary biology, and vice versa depends on these differences. For a neo-Darwinian evolutionary theory, contributions from functional and ecological morphology are indispensable. Of ultimate importance are the notions of internal selection and constraints in the constructions determining further development. In this context the concepts of random variation and natural selection need more detailed definition. The study ends with a recommendation for future research founded in a system-theoretical or structuralistic conception.

Adaptation, Physiological↗
PubMed1979

Skull growth after partial prospective lower beak extirpation in chick embryos.

On one side of chick embryos in stage 28, part of the prospective lower beak or the entire prospective lower beak anterior to the buccal corner was removed surgically (CLB-A and CLB-B embryos, respectively). In another group the prospective lower beak was split in the midsagittal plane (CMS embryos). The controls were shame-operated embryos (CS). The skulls of stage 39 CLB-A and CLB-B embryos showed changes in the lower beak as well as in the skull base, the pterygoid, the quadrate, the palatine, and the upper beak. Stage 39 CMS embryos showed shortening of the dentary and Meckel's cartilage. At the tip of the CMS mandible, an excessive amount of osseous material was found. The results support Dullemeijer's (1974) views concerning the issue of dependency of functional components. The value of a combined developmental and functional approach to morphology, i.e., integrated investigation of development of structure and function of the beaks and related jaw musculature, is discussed.

Animals↗
PubMed1977

[The holistic base of functional morphology (author's transl)].

Following v.d. Klaauw a functional component (fc) is the complex of a function and its constituent morphological features. The relation between form and function within a fc and, especially, the interrelations (pattern, compromise, integration) of the fc's constitutes the field of holistic functional morphology. The methodology of this approach is discussed.

Anatomy, Veterinary↗