November 21, 1902.] 



SCIENCE. 



81] 



to be the cause of our acute dysenteries, 

 and recently in Baltimore Duval and Bas- 

 set, working with the aid of the Rockefel- 

 ler Institute for Medical Research at the 

 Thomas Wilson Sanitarium for Children, 

 have discovered that this same bacillus 

 is in all probability the specific agent of 

 infection in the summer diarrhceas of in- 

 fants. 



Bacteriolytic serums have been used by 

 Pfeiffer in the differentiation of cholera 

 and allied spirilla, but few other bacteria 

 present equally well the Pfeiffer reaction, 

 which is not nearly so useful or handy a 

 means of identification as the Gruber- 

 Durham reaction. 



Of other cytolytic serums the hsemolysins 

 have been by far the most carefully studied. 

 One of the most interesting results of this 

 study has been the determination by pre- 

 cise quantitative methods of resemblances 

 and of differences between red blood cor- 

 puscles which in no other way could be 

 distinguished. These resemblances and 

 differences relate to the red corpuscles not 

 only of dift'erent species of animals, but 

 also to those of individuals of the same 

 species. Although we constantly assume 

 the existence of cellular differences between 

 individuals and between species, these are 

 for the most part of so subtile a nature as 

 to elude our methods of observation. The 

 exact demonstration of such differences by 

 the use of cytolytic serums is therefore of 

 especial interest. My assistant, Dr. H. T. 

 Marshall, in an unpublished research, con- 

 ducted vinder the direction of Professor 

 Ehrlich and Dr. Morgenroth, upon the re- 

 ceptors of the red blood corpuscles of man 

 and of two species of monkey, found that 

 while man and the monkeys each have re- 

 ceptors not shared by the other, they also 

 have a large niunber of receptors in com- 

 mon. 



This result is in harmony with Nuttall's 

 interesting observations on a much more 



extended scale regarding phylogenetic 

 relationships between animal species, as 

 shown by the reaction of their blood with 

 the specific precipitins discovered by Tchis- 

 towitch and Bordet, and introduced into 

 practical medicine by Wassermann. This 

 biological test to determine the source of 

 blood, when used with proper precautions, 

 far surpasses in accuracy all other methods 

 for this end. While it would lead too far 

 from my purpose to follow this subject 

 farther, I cannot in this connection for- 

 bear at least mentioning one of the earliest 

 and most suggestive papers on this class 

 of antibodies— that 'On Immunity against 

 Proteids,' by Walter Myers, who gave up 

 his life in the cause of science and of hu- 

 manity, and whose early death is so great 

 a loss to English medical science. 



I shall ask your attention now to some 

 considerations concerning the bearing of 

 recent studies of immunity on the nature 

 and action of toxins. This subject is, of 

 course, of the greatest pathological as well 

 as bacteriological importance, and I believe 

 a closer cooperation than now exists be- 

 tween bacteriologists and pathologists in 

 its study would further the surer and more 

 rapid advancement of our knowledge about 

 it. One misses only too often in purely 

 bacteriological papers on this subject exact 

 knowledge and descriptions of pathological 

 conditions, and, on the other hand, pathol- 

 ogists often fail to utilize pertinent facts 

 and ideas which are familiar to bacteriol- 

 ogists. . 



The discovery by Roiix and Yersin of 

 the diphtheria toxin, the studies by Behr- 

 ing and Kitasato of tetanus toxin leading 

 up to Behring's epochal discovery of anti- 

 toxin, and the later investigations of Ehr- 

 lich on the constitution of diphtheria toxin 

 and the origin and mode of action of anti- 

 toxin are the great events in the most bril- 

 liant and securely founded chapter of mod- 

 ern studies of immunity. Through these 



