146 Embryology and Growth of Fishes 



of growth (usually four years) before spawning. After this act 

 all the individuals die so far as known. In Japan and China 



Fin. 111. — Headfish (adult), Mnln mola (I.iiinanis). Virsrinia. 



the Ice-fish (Salaux), a very long, slender, transparent fish allied 

 to the trout, may possibly be annual in habit, all the indi- 

 viduals perhaps dying in the fall to be reproduced from eggs in 

 the spring. But this alleged habit needs verification. 



Tenacity of Life. — Fishes dift'er greatly in tenacity of life. 

 In general, fishes of the deep seas die at once if brought near 

 the surface. This is due to the reduction of external pressure. 

 The internal pressure forces the stomach out through the mouth 

 and may burst the air-bladder and the large blood-vessels. 

 Marine fishes usually die very soon after being drawn out from 

 the sea. 



