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From the viewpoint of 2007, one can trace the history of an interesting and contentious trend in biogeography and evolution that began with Croizat’s concept of panbiogeography in 1958. After a quiescent period of about 16 years, some young biologists in New York and in New Zealand read Croizat’s books and became enthusiastic supporters of his ideas. In New York, in the early 1970s, panbiogeography was combined with a part of Hennig’s phylogenetic method to create vicariance biogeography. In 1986, the name of the latter was changed to cladistic biogeography. In the meantime, Croizat’s followers in New Zealand sought to maintain panbiogeography in its original form without reference to phylogeny. This idea reached its peak of popularity in 1989–1990 and then began to fade. In comparison, cladistic biogeography became much more widespread, especially when its followers began publishing laudatory books and papers. Its decline became noticeable after the turn of the century as the dispersal counterrevolution began to have its effect. It served a useful purpose by engaging the interest of young biologists who otherwise may not have become aware of biogeography.

The Bernoulli head/disk interface is investigated using interferometry as well as the measurement of acoustic emission, normal force, and disk deflection. The dependence of head-to-disk spacing on radial head position and velocity for upper and lower heads is measured by monochromatic light interferometry. Acoustic emission measurements are used to study intermittent contacts between head and flexible disk. The normal force between the head and the disk h measured and is found to correlate with the acoustic emission signal. The disk deflection characteristics show that the normal force at the head/disk interface is related to the vertical displacement of the head. The normal force at the head/disk interface is determined from the relative disk deflection using the disk stiffness in the normal direction and compared with the measured force. Presented as a Society of Tribologists and Lubrication Engineers paper at the ASME/STLE Tribology Conference in San Diego, California, October 19–21, 1992

The vascularity of 107 primary cutaneous melanomas has been characterized by morphometric histological analysis. The lesions selected for study were of thickness 0.85-1.25 mm and the aim was to evaluate the prognostic significance of tumour vascularity. Two groups of patients were identified; 86 with no evidence of recurrence after a minimum follow-up period of 5 years and 21 with locoregional recurrence and/or metastasis. The lectin Ulex europaeus type I was used for endothelial cell staining of tissue sections and morphometric analysis was performed to derive the vascular length, surface and volume density from independent measurements of tumour, adjacent dermis and the junctional zone between tumour and underlying tissue. A wide range of values was obtained for each parameter with increased vascularity always found at the tumour base compared with the tumour as a whole. In relation to the adjacent normal dermis, vascularity was generally found to be higher at the tumour base but either higher or lower in the tumour overall. Tumour recurrence could not be predicted by any of the derived vascular parameters either independently or together with other histological and clinical features. This study suggests that tumour vascularity is of no prognostic significance in melanoma of the above thickness range. The highly variable extent of tumour vascularity was not correlated with other clinical or histological parameters, but may have implications for the delivery of pharmaceutical agents used for diagnosis or therapy. Images Figure 1 Figure 2

EDITOR, - Tony Smith asks why the French have such a low incidence of coronary heart disease and, by implication, why the Scots have such a high incidence.1 I believe that a partial explanation is the …

Head-to-disk spacing in a flexible disk drive (Bernoulli technology) is measured interferometrically using monochromatic light in conjunction with a grey level interpolation scheme. Measurements in the center region of a Bernoulli head indicate that the minimum head-disk separation is less than 50 nm, suggesting that the asperity contacts occur in the area of the closest approach. The spacing distribution of a typical Bernoulli head is reported, as well as a parameter study of spacing as a function of rotational speed. >

For the past decade, the scientific and popular press have carried frequent articles about a catastrophic mass extinction that supposedly destroyed the majority of the earth's species, including the dinosaurs, approximately 65 million years ago. Since 1980, more than 2000 papers and books have dealt with some aspect of a mass extinction at the Cretaceous-Tertiary (K/T) boundary. One authoritative estimate of the severity of the extinctions is that 60-80% of all the living species became extinct at this boundary (Raup 1988). There appears to be a general acceptance of the fact that such a great catastrophe did occur. Most of the argument among scientists now is devoted to the determination of the cause. In this article, I argue that the species changes at the K/T boundary were neither sudden nor catastrophic. They were most likely caused by a regression of sea level that led to a decrease in primary production.

After treatment for primary clinical Stage 1 invasive cutaneous malignant melanoma, 1086 patients were followed for a minimum of 5 years from initial operation. Patient data were retrieved from the unit's melanoma registry; 96 (8.8 per cent) were treated initially by incisional biopsy, 292 (26.9 per cent) by narrow margin excision biopsy and 698 (64.3 per cent) by wide margin excision. Logistic regression analysis was performed to assess the statistical significance of the association between the various factors. The method of initial biopsy was related to maximal tumour thickness, age, and sex. Incisional biopsy rendered 38 out of 96 (40 per cent) lesions not fully assessable on current histopathological criteria, significantly higher than for the other biopsy techniques (P

In a minimum 5-year follow-up study of 638 primary clinical Stage I invasive cutaneous malignant melanomas (excluding lentigo maligna melanomas) excised with conventional wide normal tissue margins, the incidence of local tumour metastasis was 48/638 (8 per cent). The incidence of locally metastatic tumours rose from 2 per cent for tumours < 0.99 mm thick, to 14 per cent for tumours between 5 and 6 mm in thickness. The rate of local metastasis was significantly greater for tumours > 2.0 mm compared with tumours < 2.0 mm thick (P < 0.01). Despite the anatomical restrictions to wide resection margins in the head and neck, these areas had the lowest regional incidence for local tumour metastasis (2 per cent). Over the prolonged postoperative follow-up period (median 11 years) 67 per cent (32/48) of patients with locally metastatic disease died of disseminated malignant melanoma, compared with a 31 per cent mortality (180/590)for those without local disease metastasis. The term ‘local recurrence’ is unhelpful in our attempts to understand the pathology of malignant melanoma, and the term ‘local metastasis’ could replace it with benefit.

Some of the facilities available with a commercially purchased word processing program, linked to a DEC PDP 11/23 computer are described, together with an account of the practical histopathological use. The system is based on a share of the computer with a Clinical Chemistry Department. Development was time-consuming and required the constant availability of the Department of Physics. However, once working, considerable saving in secretarial time has resulted and a number of projects have been started which would not have been contemplated without the use of the word processor and its linked computer.

Ten patients are presented with tumours complying with the criteria established by the World Health Organization for `mixed tumours of the lung9. A slowly growing intrabronchial neoplasm indistinguishable from a pleomorphic adenoma (mixed salivary tumour) and a peripheral circumscribed tumour with most of the features of a chondromatous hamartoma were considered benign. Of eight malignant neoplasms two were regarded as `pulmonary blastomas9, one with a benign epithelial tubular component and the other with cytological evidence of malignancy in the tubular epithelium; in both, the stroma was `embryonic9 and pleomorphic. Three tumours were considered carcinosarcomas with a mainly epidermoid epithelial component and a pleomorphic spindle-cell connective tissue component. In the remaining three tumours the malignant epithelial component showed mixed, viz., epidermoid, tubular, and a variety of undifferentiated appearances, while the `stroma9 exhibited features seen in both blastomas and carcinosarcomas. These three neoplasms were considered `transitional9. The spectrum of appearances encountered constitutes, in our opinion, a serious objection to the thesis that peripheral pulmonary blastomas and carcinosarcomas are distinct entities with a separate histogenesis. Exceptions were found to `blastomas9 being peripheral and carcinosarcomas being central growths. A case is made for reclassification of the benign and malignant neoplasms included in the WHO group IX `mixed tumours of the lung9.

In a retrospective review of 614 primary Stage I cutaneous malignant melanomata and 40 nonmelanoma lesions, the diagnostic accuracy(DA) for malignant melanoma was 86.2%. A positive preoperative clinical diagnosis of malignant melanoma was confirmed histologically in 564/604 (93.3%) of lesions. For 614 histologically proven malignant melanomata a correct pre-operative clinical diagnosis had been made in 564/614 (91.9%). An additional 172 patients were referred for wider excisional surgery within 3 months of a biopsy elsewhere. For the total 786 (614+172) patients, the incidence of biopsy of a clinicially unsuspected (but subsequently histologically proven) malignant melanoma prior to referral to the Plastic Surgery Unit was lowest for lesions of the head and neck (18.3%) and lower limb (19.0%), and highest (almost half of the patients) for lesions of the hands and fingers. Previous reports of the poor level of clinical diagnostic accuracy in cutaneous malignant melanoma have not been confirmed in the present study.

Antitropical distributions of continental shelf, Indo-West Pacific species are probably not due to transgression of the tropics during the glacial periods, isothermic submergence, island integration, rising Neogene temperatures, or the Mesozoic dispersal of fragments from a Pacific continental mass. Characteristics of common antitropical patterns, plus information from systematic works on a variety on a variety of animal and plant groups, indicate that the long discarded "relict theory" of Theel (1885) appears to best fit the evidence, for it provides a mechanism whereby antitropical distribution may be brought about. The relict theory is compatible with the concept that the East Indies part of the Indo-West Pacific has been functioning as a center of evolutionary origin. It suggests that antitropical and associated disjunct patterns are produced as an older species, that has spread out to occupy a broad range, loses ground and gradually becomes supplanted by a younger species that had subsequently evolved in the East Indies. As this process goes on, the older species becomes restricted to a few isolated localities on the fringe of its original range. These isolates are often found to the north and south of the equatorial region but may include relict populations at the western edge of the Indian Ocean.

Geophysical maps depicting continental movement have consistently shown India, as it moved northward, to be located far out in the Tethys Sea. India split off from the African east coast about 148 m.y.a. From that time onward, according to almost all geophysical accounts, India was isolated from all of other continents until the early Miocene when it made contact with Eurasia. But the biological data, both fossil and Recent, indicate that this concept cannot be correct. If India had really existed as an isolated, oceanic continent for about 100 m.y., it should have developed a peculiar biota with many endemic genera and families in its terrestrial and shallow marine habitats. But there are virtually no remains of organisms indicating that India was isolated for any substantial time (millions of years). Instead, we find that almost all Indian taxa were possessed in common with other continents. As time went on, the northern relationships became stronger and the southern ones weaker. Most of the recent geophysical accounts show India not making contact with Eurasia until the early Miocene, but fossil materials show that this event must have taken place by the early Eocene. It has been postulated that, as India moved northward, it created a biogeographic barrier that separated marine fish populations and resulted in the east-west provinces that are now apparent in the Indian Ocean. At the same time, the barrier effect was supposed to have resulted in the formation of sister species that are now located far apart. Information currently available indicates that most living, tropical marine species are probably not over 3 m.y. old. Consequently, the northward movement of India, which took place primarily between 148 and 50 m.y.a., could have no bearing on the relationships of modern species.

Primary extrapulmonary tumors with histologic features indistinguishable from bronchogenic oat cell carcinoma are appearing with increasing frequency in the literature. These tumors have been described in the esophagus, stomach, pancreas, larynx, hypopharynx, salivary glands, nasal cavity and paranasal sinuses, thymus, small and large bowel, uterine cervix, endometrium, breast, prostate, urinary bladder, and skin. It is now widely believed that oat cell carcinoma is a poorly differentiated counterpart of carcinoid tumor and that both originate from an endocrine cell system. In this article, the authors review all cases of extrapulmonary oat cell carcinomas, which they were able to find in the English literature, and report personally studied examples of these tumors, occurring in the esophagus, stomach and urinary bladder. A closely related, if not identical, tumor arising in the skin is also described. It is emphasized that a wider recognition of these tumors is likely to lead to their more frequent diagnosis and possible treatment.

281 patients managed for primary clinical Stage I invasive cutaneous malignant melanoma at one Plastic Surgery Unit were followed up to a minimum of 10 years after primary surgical treatment. Sixty-three (23%) had received an initial biopsy procedure prior to definitive wide margin excisional surgery. One third of all lesions initially treated by so called incisional biopsy were rendered histologically unassessable on current histopathological criteria. Incisional biopsy significantly interfered with the accurate histopathological staging of the tumours. Of the assessable incisional biopsy specimens the majority were greater than 4.0 mm thick. When the incidences of local tumour recurrence and mortality were related specifically to maximal tumour thickness of the primary lesion, prognosis at minimum follow up of 10 years was not significantly different between patients treated initially by either incisional biopsy, minimal margin excisional biopsy or primary wide excisional surgery. Whether or not incisional biopsy adversely affects prognosis in cutaneous malignant melanoma, the technique should be avoided since it compromises accurate histopathological microstaging which represents one of our most valuable prognostic guides. Clinical doubt over the diagnosis of cutaneous malignant melanoma should be resolved by a total excisional biopsy of the lesion in question.