22 



Francois Bourliere 



production per female and per year of North Sea haddocks 

 was found by Raitt (1932) to be 31,000 eggs for the second 

 year of life, 159,000 eggs for the fourth year of life, 278,000 



number 

 of eggs 



SO 



40 



30- 



20 



10 



30 



AO 



50 



60 



70 



SO 



90 



100 cm. 



Fig. 2. The variation with age of egg production in a 

 snake, Natrix natrix. 



eggs for the sixth year of life and 3,295,000 eggs for the 

 eleventh year. As in snakes, there is nevertheless some 

 evidence of a slight decline in egg production in the oldest 

 females. In small and short-lived species there is also some 



number 

 of eggs 



Fig. 3. The variation with age of egg production in a snake, the 

 Californian rattlesnake. Note the difference in the pattern of 

 reproductive senescence between the snakes and the fowl. A 

 senile decline in egg production in longest (i.e. oldest) females is 

 nevertheless perceptible in rattlesnakes. 



indication of reproductive failure with increasing age, but 

 accurate figures are unfortunately lacking. However, the 

 difference in the pattern of reproductive senescence between 

 warm-blooded and cold-blooded vertebrates remains obvious 



