Part of the paper is a study of the empiric practice of gradual thawing frozen extremities. In exps. in which legs of dogs and ears of rabbits were frozen stiff with CO2, bilaterally, and thawed rapidly on one side and gradually on the other, no marked difference in the subsequent incidence of gangrene was noted in the 2 cases.[long dash]Under certain conditions freezing and cold cause a marked lowering of general body temp. Citation is made of Reincke''s case of a man with a temp. of 24[degree] C who ultimately recovered, and of one animal in the present study with 24.1[degree] C (75.4[degree] F) 6 hrs. before death by bleeding. These observations indicate that even the higher mammals may have their temp. regulatory mechanism broken down under a sufficiently severe strain. Under exp. laboratory conditions a localized portion of the body may be frozen without a predominant general chilling. Under these circumstances a marked exudation of plasma-like fluid into the local tissues occurs with thawing, resulting in blood concentration, lowered bleeding volume and decrease in arterial blood pressure. This condition resembles the secondary shock following burns and indicates the similarity in action of different types of thermal injury. Under special conditions the same might occur in man.