It has been found that three different strains of an organism supposed to be Bacillus influenzæ will, under certain conditions, abandon the usual bacillary form and grow as a frank fungus, morphologically of the Discomyces type. Under other conditions they show less modification, the most striking feature then being the production of conidiospores, bodies of a type not found in true bacteria. That this organism may not be the true Pfeiffer bacillus is conceivable, of course, but considering the source, morphology, ordinary cultural characteristics, and the poison production of the one strain tested, we consider this highly improbable. Further, we are confident that the cultures do not contain any contaminating organisms, as may be suggested. In short, we believe that we have been dealing solely with the true Pfeiffer bacillus.
While these observations are of considerable interest as a contribution to the biology of the bacteria of this general type it cannot, of course, be predicted that they will prove to be of any significance as regards the true causative agent of epidemic influenza. Experimental work with this organism, apparently negative so far as reproducing true clinical influenza is concerned, has been carried out with the bacillary form exclusively. It may be found that its physiological capabilities in another phase are essentially different. This is a general biological law and there is no evident reason why it should not hold true here.
It remains to be determined whether the relatively high, complex forms described have any relation to those that occur while the organism lives among other organisms on the respiratory mucosa or acts as a tissue invader. While it seems improbable that they should develop in the animal body, that is while the organism is living as a parasite, it is at least possible that the bacillus may, under some conditions, undergo some analogous or at least similarly radical modification. If this supposition is true its cultivability might well be quite different from that of its bacillary phase, in which event it might be present in abundance and yet not be found in ordinary cultures or be recognizable in films.
But the more important problem would appear to be whether it can assume a simpler phase. If, as some believe, some of the infectious bacteria and fungi can do this, whether it be as minute, filter-passing, formed elements or as a more or less amorphous ("sym-plastic,"16 "crytoplasmic,"15) substance, an organism that is capable of as remarkable a range of morphological development upward might well go to the other extreme from the mean, bacillary stage. Whether or not this occurs and if so under what conditions are questions that deserve through investigation.