Abstract
Summary and Discussion
1. Embryonic chicks are apparently not susceptible to infection with this avian virus, although birds just hatched are. This is a strikingly reversed state from that which prevails in the case of certain other viruses, 5 which multiply readily in the undifferentiated tissues of the developing embryo but are inactive in the hatched chick. Whatever the reason may be, a fact of epidemiological significance emerges: the disease-agent is probably not transmissible by way of the egg, thus supporting the prior finding of Jones. 1
2. The virus multiplied in minced whole-embryo tissue-cultures in vitro only under certain indicated conditions. The method in its present state, however, is not favorable for obtaining large yields of highly potent virus for use in immunizing procedures. No multiplication of virus was noted in this medium when chick-embryo brain was used instead of whole-embryo tissue. It is of interest in this connection that mammalian embryo-brain cultures have been found suitable for the multiplication of the neurotropic viruses of poliomyelitis 6 and of rabies. 7
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