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The remarkable predilection shown by certain species of microbes for certain hosts, and the relative indifference of these parasites to other organisms, has long been the subject of zealous speculation and inquiry. Great as has been the advance in our knowledge of the underlying causes of natural immunity during the last few years, it can not be said that any final explanation is even yet in sight. It is, indeed, apparent that the ardent prosecution of studies into the germicidal and antitoxic qualities of immune sera has caused a temporary suspension of activity in other lines of investigation. The broader biologic aspects of natural immunity sometimes have been neglected. It may well happen that studies in plant pathology will be found to throw light on some of the questions of animal parasitism that have hitherto been shrouded in obscurity. For some time botanists have known much concerning the various modes
THE ORIGIN OF PARASITISM.. JAMA. 1905;XLIV(1):43-44. doi:10.1001/jama.1905.02500280049011