Methods of collecting sterile bovine plasma have been developed. These are applicable both to small-scale and to large-scale use. Methods of preparing bovine albumin have been studied. It is shown that methyl-alcohol fractionation maintains sterility better than fractionation by ammonium sulfate. Fractionation by electrophoresis could not be carried out in complete sterility. A survey has been made, involving 8000 skin-tests in 350 men, of the incidence of cutaneous reactions to 8 animal

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... , to the separated albumin and globulin of bovine plasma, to products of bacterial metabolism in such materials, and to various preservatives. Individuals who react to the plasma-proteins of one animal species do not necessarily react to those of other animal species. Cross-reactions are few. The incidence of positive reactors to bovine albumin is markedly less (2.6 per cent) than to the whole bovine plasma (12 per cent). The severity of the reactions is also less. Pseudoreactions are readily produced by the products of bacterial metabolism in these materials, even when the contamination has been relatively small, the period of incubation short, and the temperature low (5 C). A number of common serum-preservatives produce a high incidence of pseudoreactions. Phenol and methyl-para-sept produce the smallest number of pseudoreactions.