THE EPIC OF EVOLUTION 



491 



. /(/// "' \nturiil Histnry 



A deep-sea group of fish : left, Macrurid, 

 and right, Brotulid. 



and the larvae of certain insects 

 that are adapted to live in hot 

 springs, the temperature of which 

 is sufficient to coagulate the pro- 

 toplasm of most organisms. Some 

 animals, frogs for example, can 

 survive a degree of freezing that 

 would be fatal to others. Trees 

 and woody shrubs can successfully 

 withstand low temperatures that 

 cause most of the less woody 

 plants to succumb. The varying 

 range of frost and heat to which 

 plants of different sorts are sus- 

 ceptible is common knowledge to 

 every farmer. 



Adaptive devices, such as gem- 

 mules of fresh-water sponges, the 

 winter eggs of daphnids, and the 

 statoblasts of certain bryozoans, 



carry these lowly animals through the freezing winter into another 

 summer quite as effectively as the various coats and shells of seeds 

 and nuts. Again, warm-bloodedness is an adaptation fitting birds 



and mammals to cope successfully 

 Avith great and often sudden shifts 

 in temperature on land, to which 

 the cold-blooded inhabitants of 

 water are not subjected. 



Pressure is another physical 

 factor to which every organism, 

 in order to live, must be adjusted. 

 Most animals and plants living on 

 the surface of the earth, beneath 

 a uniform blanket of atmosphere, 

 are not subjected to much differ- 

 ence in pressure, but deep-sea 

 fishes, with an additional weight 

 of superimposed water, have quite 



American Museum of y.aturnl Histunj ^ ^ ; -i 



Oceanic angler fish, Linophryne. The a different problem to meet. This 

 beard is probably luminous. particular form of adaptation 



