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been purified approximately 300 fold by absorption and elution from diethylaminoethyl (DEAE) cellulose (12) followed by precipitation with 55-percent saturation of ammonium sulfate at 0?C. Moreover, when DEAE cel? lulose is developed with a linear NaCl gradient, the corresponding variant and normal LDH isozymes are eluted at similar points. The mobility of normal and variant LDH isozymes from crude hemolyzates is identical in the sys? tem (75) of varying starch-gel porosity. Such behavior suggests that the molecular weight of normal and variant isozymes is grossly similar (14). The enzymic activity of variant LDH from crude hemolyzate approximates that ob? served in normal American and Nigerian Negroes. The only blood relative available for testing, a paternal uncle, has a normal LDH pattern. Whatever the origin of the observed LDH variation, it is uncommon (75) since no variant LDH patterns were observed among hemo? lyzates obtained from approximately 50 white subjects, 300 American Negroes, 100 Papuans (16), and 200 Nigerians. Fritz and Jacobson (17) examined mouse tissue extracts and observed five LDH-5 components, four LDH-4 com? ponents, three LDH-3 components, two LDH-2 components, and one LDH-1 component in gels prepared with 0.005M /?-mercaptoethanol. These au? thors suggest that this concentration of /?-mercaptoethanol removes bound NAD from a portion of A subunits but not from B subunits. These ob? servations provide a pattern exactly opposite to that in the Nigerian LDH variant. Moreover, the human variant LDH pattern is unaltered in gels con? taining /3-mercaptoethanol in amounts ranging from 0.005 to 0.1M. The vari? ant LDH pattern is also unaltered by electrophoresis under conditions where the gel and cathodic chamber contain 10~3M NAD. Accordingly, we do not believe that the variant pattern is pro? duced by the mechanism of differential binding of NAD. The variant electrophoretic pattern can be most easily interpreted as reflect? ing a mutant allele at the genetic locus producing the LDH B subunit. The observed physical and enzymatic similarities between normal and variant LDH-1, that is, B subunit tetramers, support this interpretation. If the mu? tant product is designated /?, and the normal product B, then a heterozygote at this locus should exhibit the combi? nations shown in the third column of As work continues the sweating rate may then be controlled by thermal factors, such as increased core or hypothalamic temperatures. In cooler environments the same nervous stimuli may be present, but inefTective because of inhibition by the cooler temperature (77).

The local organ or tissue blood flows during the process of arousal from hibernation have been estimated in the 13-lined ground squirrel by the Sapirstein method, which consists of the measurement of the regional distribution of injected rubidium 86. The studies demonstrated that during arousal there is a confinement of blood flow to the thoracic regions. After the heart rate has attained 100 beats/min, blood flow increases to the anterior portions of the animal. At the arousal level characterized by a heart rate of 200 beats/min, blood flow to anterior and thoracic tissue had attained levels almost equal to control flows. Posterior tissue flows were still much lower than control flows. The centralization of blood flow to thoracic and anterior tissues did not occur in the rat in the hypothermic state.

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