Clxxxi . Studies on Diffusing Factors . Iii

THE presence of diffusing factors in snake venoms has been demonstrated by Duran-Reynals [1936, 1939]. The immediate effect of intracutaneous injection of indicator solutions containing rattlesnake venom is similar to that of solutions containing testicular diffusing factor [Madinaveitia, 1939], namely,. an almost instantaneous flattening of the resulting bleb with rapid spread of the indicator through the skin tissue. About 1 hr. after injection, however, a difference is observed between the two; the rate at which the area of spread increases becomes extremely slow in the case of testicular diffusing factor while it is still relatively rapid with the rattlesnake venom solution (Fig. 1). This secondary