Two possibilities may be considered for the mechanism of the immediate capillary stress response: the direct nervous origin, and the humoral. The latter was investigated in this study. Immediate capillary stress response was found in the absence of the adrenal, pituitary or thyroid glands, and after removal of both the adrenals and the pituitary. Among the 10 physiologic substances considered as playing a potential role in this phenomenon, three were found to possess capillary activity. Vasopressin as well as oxytocin increases capillary resistance. Histamine gives rise to a biphasic response, involving a decrease of capillary resistance (primary effect) followed by an increase (due to vasopressin elicited by histamine). By means of these substances it is possible to duplicate the immediate capillary stress response. During the immediate capillary response plasma has antidiuretic and chloruretic properties—a finding compatible with an increased vasopressin concentration and with the assumption that vasopressin is discharged rather regularly in the first phase of the stress response. The immediate capillary stress response seems to be the result of an interplay between vasopressin-oxytocin, and histamine. Species and individual differences in the sensitivity to these substances may account for the various patterns of the capillary response. The possible significance of the immediate capillary response and of the increased vasopressin activity in some clinical conditions is discussed.

serum treatment in ooo died without evidence of anomalous development, despite the fact that virus could be recovered from their tissues. A possible explanation for this phenomenon lies in the knowledge that the chick embryo is susceptible to lethal infection with this virus for at least the first 2 weeks of development, while the period of susceptibility to the teratogenic effects of the virus is restricted to about the first 48 hours of embryonic development.Conciusions. Specific immune serum will protect the 48-hour chick embryo from the teratogenic and lethal effects produced by infection with influenza-.\ virus. Inasmuch as antiserum can neutralize these effects completely in vitro, and to a lesser extent in OVO, this study provides serological evidence to implicate the virus as the cause of the syndrome described.