=Conclusions on Pollen Extracts.= My conclusions on the pollen treatment are that it is in line with our best practice of immunity but that it is still in an experimental stage, the pollens are possibly dangerous even in the hands of a skilled immunologist. In a disease that is usually so easily controlled by rosin-weed, faradism and ichthyol, I would not expose a hay fever patient to the very real danger of anaphylactic shock. The conditions governing immunity stated in the beginning of this chapter still hold good. It is transient. Already some of the early workers have discontinued the practice. The despair of Goodale has been quoted. Scheppegrell, probably the first in this country to use the pollens, has given them up and advises the patient to keep away from his irritant and to have the weeds cut in all cities as the best treatment obtainable (_Journal of the A. M. A._, March 4, 1916, page 710). The most hopeful aspect of the pollen extracts seems to me to be their administration all around the year in high dilutions, _more homoeopathico_, and to this practice I believe the immunologist will eventually come. =Pollen Extracts not Vaccines.= Some manufacturers and all British writers speak of pollen extracts as _vaccines_ and of immunizing the patient as _vaccination_. This seems an unnecessary confusion. We have two kinds of vaccines already, the cow-pox vaccine and the killed cultures of bacteria introduced by Wright. For an account of the use of these vaccines in hay fever, we will pass to the next chapter. CHAPTER XII _THE BACTERIAL VACCINES_ In his paper in _The Lancet_, the pioneer in the use of pollen extracts, Freeman, observed that "many cases of supposed hay fever" were simply acute bacterial catarrhs. He excluded hay fever by the lack of any reaction when timothy extract was dropped into the eye. The bacterial infection was proved by culture from the eyes and nose, usually yielding the staphylococcus. The final proof was the cure of the patient by an autogenous vaccine made of the offending microbe. In the past few years, this observation has been confirmed and many cases of cure of "hay fever" by bacterial vaccines have been reported in the journals. The bacteria were chiefly staphylococci, rarely the pneumococcus or the micrococcus catarrhalis. Oppenheimer and Gottlieb report cases of mixed hay fever where the skin reacts to pollen but the pollen extract failed to cure. In these cases, they found a bacterial catarrh of the eyes and nose. They suppose a vicious circle, the catarrhal inflammation and the hay fever sensitiveness mutually interfering with each other's recovery and they succeeded in curing the patient by using the appropriate pollen extract and the bacterial vaccine at the same time, believing that while the pollen extract was raising resistance to the pollen poisoning, the bacterial vaccine was raising resistance to the bacterial catarrh.