HEMINGWAY, A. 
For protection against cold, the homeothermic animal can 
increase its heat production by shivering to a value as much as 
four to five times the resting heat production. In a recent paper 
where shivering was studied on man, lampietro, Vaughan, Goldman, 
Masucci, and Bass (1960) found the maximal shivering heat pro- 
duction rate to be 442 Cal/hr, and with a resting nonshivering heat 
production rate of 80, the heat production rate was increased to 
5.5 times the resting nonshivering value. This value is, however, 
maximal and usually the heat production rate observed during 
shivering is two to four times the nonshivering value. In fact, the 
regulation of shivering is so well adjusted to temperature regu- 
lation demands that the shivering can be mild, moderate, or intense 
as required. Nonshivering thermogenesis, the term applied to an 
elevation of heat production caused by cold without shivering, can 
elevate the oxygen consumption rate from 10 to 20 percent in the 
larger animals and possibly more in the small mammals and birds. 
The other physiological protection against cold, the thermal cutan- 
eous vasomotor response, is the nervous control of the diameter 
of the blood vessels in the skin. Contraction of the smooth muscle 
of the cutaneous arterioles causes vasoconstriction and reduces 
blood flow through the skin. The skin temperature is lowered and 
heat loss from the skin is reduced. 
Methods of Testing Physiological Responses to Cold 
Before the details of the neural control of the physiological 
responses to cold are described, the methods for testing these 
responses will be reviewed briefly. The following methods are 
those which have been used by investigators for testing the functional 
activity of the various components of the temperature regulating 
system . 
Cold exposure test (test for homeothermy). An animal is placed 
in a cold environment, usually a cold room having a temperature 
of from C to 15 C, and its rectal temperature measured at 
