November 28, 1902.] 



SCIENCE. 



859 



and that in this field they have borne their 

 richest fruits. It is especially gratifying 

 to note the close convergence of the two 

 doctrines of immunity, the cellular and the 

 humoral, brought about by these recent 

 discoveries. On the one hand the phago- 

 cytic school, represented so brilliantly by 

 Metchnikoff and his coworkers in the Pas- 

 teur Institute, recognize and apply to the 

 fullest extent in the explanation of ac- 

 quired immunity the cytolytic principles 

 based upon the cooperative action of inter- 

 mediary bodies and complements. On the 

 other hand the humoral school, led by our 

 German confreres, which has been so fruit- 

 ful in results of the greatest scientific and 

 practical value, recognize the cells, and es- 

 pecially the leucocytes and other cells of 

 the blood-forming organs, as the immediate 

 source of the protective substances. There 

 are many differences in details, especially 

 in terminology and in interpretation, which 

 make the divergence seem greater than it 

 really is. The essential difference between 

 the two schools concerns the place where 

 the two forces, intermediary body and com- 

 plement, unite. All are agreed that the 

 intermediary body exists free in the blood 

 plasma, but Metchnikoff strenuously in- 

 sists, especially on the basis of Gengou's 

 experiments, that the complement or cytase 

 is within the leucocytes, from which it is 

 not secreted but can be liberated only 

 through damage to these cells. This ques- 

 tion certainly needs further investigation 

 before it can be regarded as settled. 



The deeper insight which we have re- 

 cently gained into the nature of the forces 

 concerned in immunity makes especially 

 desirable the systematic study of the blood 

 and other fluids of human beings in health 

 and in disease with reference to their con- 

 tent of specific antibodies, particularly of 

 the bactericidal substances. It can scarcely 

 be doubted that knowledge of this kind will 

 be in various ways of practical value to the 



physician and surgeon. The simplest pro- 

 cedure, and the one hitherto generally 

 adopted, is the estimation of the bacteri- 

 cidal power of the blood serum in toto. 

 For this purpose Professor Wright* has 

 devised an ingenious method which in his 

 hands has furnished extremely interesting 

 information concerning variations in the 

 bactericidal power of the blood as regards 

 the typhoid bacillus in health, imder the 

 influence of fatigue, in the course of ty- 

 phoid fever and after antityphoid inocula- 

 tions. The older methods, however, while 

 not without value, do not inform us of the 

 total content of the blood in immunizing 

 substances, and have led to very discordant 

 results, particularly as to the influence of 

 infection upon the bactericidal power. 

 Thus Conradif finds, in opposition to most 

 previous experimenters as well as to the 

 later results of Wilde, that infection with 

 the anthrax bacillus does not at any stage 

 influence materially the bactericidal prop- 

 erties of the blood. 



A useful and readily applicable method 

 for the determination separately of the in- 

 termediary bodies and of the complements 

 of human serum is urgently needed. When 

 one takes into consideration the plurality 

 of complements and of intermediary bodies, 

 the fallacies of interpretation which may 

 arise from failure to take account of anti- 

 complements, of anti-immune bodies, of 

 complementoids, of amboceptoids, of devi- 

 ation (Ablenkung) of complements, and 

 other principles in this complicated subject, 

 it is clear that the problem is not an easy 

 one. 



Notwithstanding these difficulties, work 

 has already begun along these new lines, 

 and has led to interesting results. We 



*A. E. Wright, Lancet, 1898, I., p. 95; 1900, 

 IL, p. 1556; 1901, I., pp. 609 and 1532, and 1901, 

 II., p. 715. 



t Conradi, Zeitschrift filr Hygiene, 1900, 

 XXXrV., p. 185; 1901, XXXVIII., p. 411. 



