!.^^^.^^■ f- 



2 



3 



m 



Plate XXX. The development of the plaice. 



I, egg with embryo developing inside; 2, the newly hatched larva with its yolk sac; 3, a later 



stage with the eye starting to come over; 4, a still later stage with the eye now almost in the 



adult position. All to same scale. 



Drawings by N. T. Nicoll 



which had been thought to be the reduced sahnity, has recently been shown 

 to be the 'smell' of the fresh water, and if the 'smell' is extracted by filtering 

 through charcoal the young eels do not react to it. (The filtering through 

 charcoal extracts dilute organic chemical substances, and is the same principle 

 as used in the wartime gas mask.) Once in the vicinity of the rivers they 



T02 



