72 LIFE IN THE SEA [OH. 



instance cats which live in cold-storage warehouses 

 have sleeker coats and are apparently healthier than 

 are animals living under normal conditions ; and it 

 is possible that the connection between length of life 

 and temperature might also be proved by comparative 

 vital statistics. However this may be, the following 

 experiment affords direct evidence of the probability 

 of the statement : sea-urchin eggs are fertilised and 

 are kept at a constant temperature, and then small 

 quantities are taken and are put into water of 

 different temperatures, and the higher the latter the 

 shorter is the life of the egg. If we call the duration 

 of life of an animal at temperature f a t , then the 

 duration of life at temperature (t n) is a t ^ n . This 

 means, supposing of course that the experiments 

 referred to should be confirmed, and prove to be 

 of general application, that if the temperature of the 

 water in which a cold-blooded animal is living is 

 reduced by 10 C. its duration of life will be increased 

 a thousand-fold. It seems too good to be true ! 



It would seem, however, that some such relation 

 between temperature and length of life of the kind 

 stated does actually exist. Now let us apply it to 

 the case of the observed density of plant and animal 

 life in warm and cold seas and we have a possible 

 explanation not the only one as we shall see but 

 still perhaps the most probable one. When the 

 temperature is reduced by 10 C. not so great a 



