30 C. HEDLEY. 



polyzoa, ascidians, echinodermata and gasteropoda also 

 suffered. In some places half the fauna was dead, in others 

 the rocks which usually swarm with life were so deserted 

 that only a few worms remained alive of a great congrega- 

 tion. Mobile creatures like fish and crabs withdrew from 

 the putrifying beach to deeper water. 



Whitelegge 1 considered that dense swarms of a micro- 

 scopic red GlenocMnium suffocated the mussels and oysters 

 by clogging their gills. The death and decay of these 

 bivalves, diffusing corruption in the water, spread destruc- 

 tion through their neighbourhood. This microbe, Gleno- 

 dinium rubrum, appeared in March and April 1891, in such 

 vast numbers as to discolour the waters of the harbour in 

 long streaks and patches of blood red. So immense a 

 development of the dinoflagellate was thought by White- 

 legge to be fostered by a heavy rainfall reducing the salinity 

 of the surface water and by a long continuance of calm 

 weather. The final disappearance of the Glenodinium was 

 due partly to the fall in autumn temperature and partly to 

 the efforts of an allied protozoan Gymnodinium, which 

 arrived to prey on it. Had the plague Glenodinium been 

 colourless and consequently invisible, the disaster would 

 have been without apparent cause. 



Certain reefs, where both animals and plants suddenly 

 and mysteriously perish, are described by the fishermen in 

 Japan as having been "burnt." On one occasion this 

 happened on so large a scale that the loss to the gatherers 

 of sea-weed for food, glue, or manure, and of fish to the 

 fishermen was estimated at £1,200 per annum per mile of 

 the infected area. Within a few days the sea-weeds on 

 these reefs were destroyed from low water downwards. 

 The softer plants rotted away, while the harder corallines 

 stood, though faded from red to white. The banks grew 



1 Whitelegge, Eec. Aust. Mus., i, 1891, pp. 179 - 192. 



