gation such a study was made of normal defibrinated pig's blood under ordinary conditions, on the one hand, and after radiation with rays of various wave length on the other hand.The tests were performed by measuring the growth of liviiig seedlings of the plant Lupinus albus immersed in definite nutrient solution with and without admixture of one per cent of blood. Specimens of pig's blood were exposed to the action of ultraviolet rays for periods varying from 10 to 30 minutes, the radia-

The Choice of Methods. In order to decide what methods we should use to demonstrate the microörganisms that might have a relationship to acute infections of the upper respiratory tract, we first investigated those previously reported for the demonstration of such organisms. We were unable, however, in the large majority of the reports to find methods given in enough detail to use them as standards for comparison. Such questions as the following, for example, were usually treated vaguely. Just how and from what areas the material for examination was collected and at what stages of the disease? What definitely described culture media were used and how were they inoculated? How were the resulting cultures handled in order to demonstrate strain relationship? From the standpoint of arranging methods, we divided the microörganisms for which claims had been made into two general groups, namely, aerobic and anaerobic microbes, subdividing each into filtrable and non-filtrable microbes.

The primary object of this study, as we have already stated, was to look for evidence of an epidemic strain among cocci of this type. With regard to this group of bacteria, perhaps more than any other, sweeping statements have been made concerning the relationship of strains to epidemics. This is largely due to their ubiquity and the difficulty of demonstrating clear cut proofs of such relationship and also to the ease with which deductions are made from insufficient evidence. The most important question relating to this subject about which we have little accurate knowledge, is the question of the permanency of those characteristics which are supposed to be indicative of species, of specific pathogenicity and of related characteristics which might be used in diagnosis. We know a little of the limits of change in vitro but essential changes in the animal have not yet been demonstrated with controls sufficiently free from error.