Abstract
If fresh, cell-free, guinea pig serum in a test tube is repeatedly frozen and thawed without shaking or inverting the tube there will be seen, after a few freezings and thawings, a difference between the upper and lower portions of the tube. If the serum is tinged with hemoglobin the lower portion will be deep red and the upper portion colorless. If there is only a trace of hemoglobin an indication of what takes place may still be shown by gently tilting the tube back and forth whereupon a transverse movement of heavy oily-looking streaks is seen, somewhere below the middle of the tube, between an amber colored lower portion and a colorless upper portion. If the lower portion is recovered and titered for complement content against sensitized sheep cells this portion will be found to have a higher titer than that of the original whole serum, the difference being greatest if only the extreme lower portion of the concentrated serum be employed. 1
In one such experiment the contents of the tube, immediately after the last thawing, was divided into 2 equal upper and lower portions and nitrogen determinations were done on the 2 halves and on the original whole serum in addition to complement titrations. The complement titer was higher and the total nitrogen content was greater in the lower half than in the whole serum. The difference in complement value was as 100 to 133; the difference in albumin as 100 to 230; in globulin as 100 to 150. The gain in complement, therefore, was associated with a change in the albumin :globulin ratio, the change consisting in a relative increase in albumin and a relative decrease in globulin.
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