(because the whole animal can be put in an NMR machine), and the use of ectothermic poikilotherms to study effects of temperature on physiology.

5. To use the "kind of animal" as an experimental variable.
: "While other branches of physiology use such variables as light, temperature, oxygen tension, and hormone balance, comparative physiology uses, in addition, species or animal type as a variable for each function."
: 25 years later, Prosser put things this way: "I like to think of it as that method in physiology which uses