Bijdrage tot de kennis der mariene fauna van de Belgische kust (III). Waarnemingen aangaande het voorkomen, de voortplanting, de settling en de groei van <i>Crepidula fornicata</i> (L.)

1. For the first time, Crepidula fornicata was observed in Belgium on 28-9-1911; in 1959, it became an oyster pest. 2. It was first introduced into Belgium with seed oysters from Great Britain. Later on, with seed oysters from the Netherlands. 3. Probably, the geographical spreading is caused by the adult animals attached to oysters. Larval propagation is responsible for local extension. 4. In the sluice-dock at Ostend, larvae occur from the middle of May till the end of November; they swim freely for a period of about 12 days. The first massive emission of larvae is observed during May and June, a second one in September. 5. The larvae settle preferentially at a depth of 65 cm. 6. Maximum settling takes place in May. It then decreases till October. 7. After two months, the animals already form chains consisting on an average of 4 specimens. 8. Maximum growth takes place from May until the end of August. After a lapse of five months, a length of 24.1 mm was recorded. 9. Only those individuals which settled in May and June persist in relatively large numbers. 10. Four-month o1d Crepidula were found incubating eggs. The number of eggs averaged 1,500

Observations sur la salissure dans le port d'Ostende

Observations on the pollution of an emerging tufnol plate over a period of 13 months (11-IV-1963/ 28-V-1964) in the harbour of Ostend: temperatures and chemistry of the environment; granulometry of the accumulated mud; inventory and evolution in the time of fouling organism

Too little, too late: reduced visual span and speed characterize pure alexia

Whether normal word reading includes a stage of visual processing selectively dedicated to word or letter recognition is highly debated. Characterizing pure alexia, a seemingly selective disorder of reading, has been central to this debate. Two main theories claim either that 1) Pure alexia is caused by damage to a reading specific brain region in the left fusiform gyrus or 2) Pure alexia results from a general visual impairment that may particularly affect simultaneous processing of multiple items. We tested these competing theories in 4 patients with pure alexia using sensitive psychophysical measures and mathematical modeling. Recognition of single letters and digits in the central visual field was impaired in all patients. Visual apprehension span was also reduced for both letters and digits in all patients. The only cortical region lesioned across all 4 patients was the left fusiform gyrus, indicating that this region subserves a function broader than letter or word identification. We suggest that a seemingly pure disorder of reading can arise due to a general reduction of visual speed and span, and explain why this has a disproportionate impact on word reading while recognition of other visual stimuli are less obviously affected