Julian Huxley (1924) came to the conclusion that intra-specific growth usually follows a sequence of power curves. So Huxley claimed that during growth sudden changes in the growth rate can occur. The restudy of his material, however, reveals that his observations closely follow single quadratic curves. As a result the intra-specific allometry studied by Huxley is comparable to ontogenetic allometry. The quadratic factor of the quadratic equations obtained, represents the growth rate; it shows the constant increase (positive factor) or decrease (minus factor) of one of the measurements for a constant increase in the other measurement with which it is compared. The quadratic factor explains the entire growth process and is the same for the smaller (younger) and larger (older) specimens. It could probably permit the prediction of the shape of larger and/or smaller animals not yet found, or give a clue to some evolutionary changes. By using the quadratic parabola there is no need to postulate “sudden changes in the growth curve” and so it appears that Huxley’s power curve can be abandoned.

Background: The study of differential growth in various animals suggests that a similar growth pattern occurs throughout the bilateral animals. This growth pattern is based on the assumption that a quadratic equation describes the relationship between two body measurements, yielding a quadratic parabola in a graphic presentation. Aim: Can human growth be studied by comparing body measurements? If the growth of one body part has a definite relation to the growth of another body part and if this relation can be expressed in a quadratic formula, then important conclusions can be reached. Subjects and methods: An official database of the mean measurements of the Belgian population has been used. Results: (1) The growth in human length is, from the beginning, constantly and negatively influenced by the growth in girth, so it is evident that growth has to stop; (2) The influence of the growth in girth is stronger in females, resulting in shorter females; (3) The growth of the human head is, from the beginning, constantly and negatively influenced by the growth in body length (both sexes show a very similar pattern); (4) Not all comparisons resulted in a quadratic parabola: the nipple distance is constantly at similar to 24% of the thoracic girth in males and young females. Conclusion: The study of differential growth by using a quadratic parabola gives the answers to the questions Why do we stop growing?' and "Why are women shorter than men?".

The Tylenchidae of the world contains full descriptions of all the nematodes reported from everywhere in the world that were considered to belong to the Tylenchidae. More than 400 species are described. The book is amply illustrated with line drawings and SEM photographs that are based on microscope and sub-microscope observations.

Five species of cyst-forming nematodes belonging to the Heterodera avenae group were identified from cereal fields and grasslands in Iran. Morphological and morphometric characters of H. avenae, H. filipjevi and a still unidentified species from the H. avenae complex and of H. latipons and H. hordecalis from the H. latipons complex are presented and their relationship with similar species is discussed. Heterodera filipjevi and H. latipons are the dominant species in cereal fields; H. avenae was found in wheat fields in only one region in the west of the country. Heterodera hordecalis was recovered from a few wheat fields and around grasses in western Iran, and Heterodera sp. from grasslands at several sites in northern and western regions of the country.

This chapter covers the taxonomy, morphology and management of ectoparasitic nematodes under Tylenchoidea and Criconematoidea (Dolichodorus, Belonolaimus, Tylenchorhynchus, Amplimerlinius, Helicotylenchus, Rotylenchus, Hoplolaimus and Criconemoides) and Enoplea (Longidorinae, Xiphinema americanum group, X. index, Trichodorus similis and Paratrichodorus minor). The phylogenetics and role of ectoparasitic nematodes as vectors of plant viruses are also covered.

Light-microscope studies revealed the presence of phasmids in the mid-tail region in species of the genera Tylenchulus, Trophotylenchulus (syn. Trophonema), Sphaeronema and Meloidoderita in Tylenchulidae. Scanning electron microscopy studies on Sphaeronema species verified these observations. Absence of phasmids or phasmid-like structures was confirmed for genera placed in Paratylenchinae and Tylenchocriconematinae in the same family, and for other taxa of Criconematoidea. This first record of phasmids in the superfamily Criconematoidea requires reconsideration of the systematic position of Tylenchulidae and of the relationships of the genera currently placed in this family. Presence of phasmids, deirids and other morphological characters place Tylenchulidae in a basal position in Criconematoidea.

Post-embryonic growth is characterized by a constant reduction of some growth parameters in relation to other growth parameters. Comparison of growth in chickens, rats and nematodes reveals an identical growth pattern, so a theory about the growth process in general is presented. It is presumed that the same growth promoting and growth inhibiting substances regulate not only growth but also ageing and that it is the equilibrium between growth promoters and growth inhibitors which is constantly changed.

A survey conducted to identify cyst-forming nematodes in Iran revealed the presence of species belonging to the genera Heterodera and Cactodera. Heterodera elachista, H. fici, H. glycines, H. goettingiana, H. humuli, H. turcomanica and Cactodera cacti obtained from different plants and regions are described for the first time from Iran. Morphological features and morphometric characters with comparative details for these species as well as for H. mothi are presented and the relationship of some of the species with similar species is discussed.

The list of Tylenchomorpha known from Belgium is updated with observations from 32 locations. Forty two species are added, of which 11 are new records for the Belgium nematofauna. Five nominal species are removed because of synonymy and the list of 161 species is presented nomenclaturally.

Summary ‐ The cellular morphology of the gonoduct of six Pratylenchus species, three Pratylenchoides species, Radopholus similis , Zygotylenchus guevarai, Hirschmanniella looe and Nacobbus aberrans was revealed by dissection and light microscopy. Except for Nacobbus aberrans , all studied species show an overall similarity in gonoduct construction, i.e., an ovary often ending with a ring of cells, an oviduct formed from two rows of four cells and a 12-celled spermatheca followed by a tricolumella containing 16-24 cells. Pratylenchoides magnicauda and Z. guevarai did not diverge from the other Pratylenchidae in this respect, although their gonoduct differs from that of Amplimerlinius and Meloidogyne , both formerly postulated as related genera. The spermatheca structure observed in N. aberranshas not been reported elsewhere in the Nematoda, although the uterus is similar to that reported within the Heteroderinae and Meloidogyninae and the uterus comprises more than 300 cells, enlarging from a tricolumella to a polycolumella. Transmission electron microscopy of Z. guevarai revealed details of the cytoplasmatic contact between epithelial cells and the germ cells; a e ngerlike ovarian wall cell extension was found penetrating the oocyte. The oviduct lacks a preformed lumen and comprises eight cells with highly plicated cell membranes. The spermatheca is constructed from e attened wall cells and is followed by columnar uterus cells where evidence of eggshell formation was demonstrated.

The cellular gonoduct structure of 97 species belonging to the Tylenchomorpha and of eight species belonging to outgroups were studied, this to explore diagnostic applications of gonoduct characteristics and their use to assess phylogenetic relationships within the Tylenchomorpha. The morphology of the spermatheca has been shown to have particular value as a taxonomic character, while the cellular arrangement of oviduct and uterus seems to be a reliable phylogenetic marker. The gonoduct of the studied tylenchs (without Criconematoidea) displays important similarities: the oviduct consists of two rows of three to seven cells; the spermatheca comprises 10 to 20 cells and the uterus cells are arranged in three or four rows. The spermatheca of Meloidogyne is formed by a variable number of thick, lobe-like cells making it distinctive from any other known nematode genus. Ultrastructural data substantiate that the Meloidogyne spermatheca and oviduct are exceedingly complex structures and that their function is broader than a simple conduit for oocytes and receptacle for sperm. In the Criconematoidea, cells of the uterus-spermatheca complex are not arranged in distinct rows and a lumen is present. The gonoduct structures of the Aphelenchidae and Aphelenchoididae are remarkably distinct from each other and from the remaining Tylenchomorpha, this does not preclude the polyphyly of the Aphelenchoidea as suggested by molecular data.

Gonads from living young females, representing 23 different species, were extracted to study the cellular structure of the female genital structure within the Meloidogyninae and Heteroderinae. All genera studied can be characterised by their cellular spermatheca morphology. Within Meloidogyne a spherical spermatheca is found with lobe-like protruding cells, most species having 16 to 18 spermatheca cells with interlaced cell boundaries while M. microtyla and M. ichinohei have more spermatheca cells with different cell boundaries. Heterodera and Globodera reveal a comparable gonad structure. The spermatheca cells of Heterodera are columnar and arranged in a restricted number of rows, whereas in Globodera the spermatheca cells are squarish to rounded, depending on the species. The gonad morphology of Afenestrata koreana is clearly different from what would be expected based on the related genera Globodera and Heterodera. The apparently simplest genital system was found in Meloidodera floridensis where the uterus has a limited number of cells. In the other genera studied a large and variable cell-number was found.