December 31, 1920] 



SCIENCE 



621 



etc., while success has been achieved in the 

 instance of epidemic meningitis, and very- 

 hopeful results have recently been attained in 

 the case of pneumonia. 



In meningitis the success is linked with the 

 recognition of a second principle of action, 

 namely the advantage to be derived from what 

 may be called the local specific treatment of a 

 disease, or the bringing of the healing serum 

 into direct and intimate relation with the seat 

 of the infection itself. Since in epidemic 

 meningitis it is the membranes surrounding 

 the brain and spinal cord and those more deli- 

 cate ones lining the cavities of the ventricles 

 of the brain which are the seat of infection, 

 it has been found easily possible, through a 

 jsimple and safe procedure, to inject the 

 serum into the cavity of the spinal meninges, 

 whence it is quickly distributed over all the 

 membranes of the brain and cord. It may be 

 of interest to remark that it is not practicable 

 to reach the inflamed membranes with the 

 serum by way of the blood, since nature, in 

 order to protect the sensitive nerve tissues 

 from injury by any chance deleterious sub- 

 stance in this fluid, has interposed an im- 

 penetrable barrier, the choroid plexus, between 

 the circulation and the cerebrospinal fluid 

 which bathes and sustains the nervous organs, 

 and which is itself elaborated from the blood 

 by this plexus with an accuracy of selective- 

 ness highly remarkable. 



In pneumonia again a beginning success has 

 been achieved through a finer discrimination 

 of specific kinds among the pneumococci, the 

 inciting microbes of the disease. This distinc- 

 tion is independent of ordinary physiological 

 and cultural characters displayed by the bac- 

 teria, which do not serve to bring out the 

 underlying specific properties of each, and has 

 been accomplished by means of the so-called 

 immunity tests carried out in test tubes or in 

 the animal body. The gain to practical medi- 

 cine from the detection of the fundamental 

 differences subsisting between the three m.ain 

 types of pneumococci existing in this country 

 has been very great. Already a curative serum 

 for one of the specific types of pneumonia has 

 been secured, and through its application many 



lives have been saved; while beginnings have 

 been made in respect to vaccination against 

 the disease when, as sometimes happens in in- 

 stitutions and in communities, epidemics pre- 

 vail and claim many victims, as occurred in 

 the Army training camps during the measles 

 epidemics of 1917-18. 



Thus we have learned that the immunity re- 

 actions, or the effects on bacteria and their 

 poisons, of the fluid and cells of the body as 

 modified by the process of artificial immuni- 

 zation, provide more delicate and precise means 

 ,of discriminating bacterial species than the 

 qualities of form, growth appearances and 

 physiological ac^tivities, and more accurate 

 methods of distinguishing poisons than the 

 most refined chemical analyses; and we shall 

 learn a little later in connection with the dis- 

 tinct but related hypersensitive or anaphy- 

 lactic state, that the prepared and sensitized 

 animal body responds to infinitesimal amounts 

 of protein matter according to its specific 

 origin, in a manner not otherwise determin- 

 able and far beyond the most delicate labora- 

 tory test which the chemist has invented. The 

 animal body thus artificially prepared, or as 

 sometimes happens naturally sensitive, ac- 

 quires an appreciation of the inner constitu- 

 tion of the protein molecule, classifying it, as 

 it were, not only according to its ordinary 

 chemical nature, but according to its species 

 origin. 



The immunity reactions we have considered 

 are not artificial creations, since as we now 

 know, they are the very processes which nature 

 employs in her unaided efforts to abate infec- 

 tions, and when need be, to adopt the body to 

 foreign proteins. The spontaneous recovery 

 from infectious disease, by which is meant 

 merely that the body by its own power over- 

 comes the microbes and their poisons, depends 

 upon the setting into motion of the series of 

 operations through which immunity responses 

 in fluids and cells are insured, precisely as has 

 been described in the event of an artificial im- 

 munization. Hence in our efforts at serum 

 therapy we aim merely to aid " nature," by in- 

 trodticing, as it were, into the beset body the 

 finished immunity products artificially pro- 



