8G0 



SCIENCE. 



[N. S. Vol. XVI. No. 413. 



know that tlie content of the blood in 

 specific antibodies, and especially in com- 

 plements, varies in significant ways under 

 diverse conditions, as in infancy and in 

 adult life, in health, in different states of 

 nutrition, under the influence of fatigue, 

 of inanition, of pain, of interference with 

 respiration, of alcohol, and in disease. The 

 infant comes into the world with protective 

 antibodies in the blood smaller in amount 

 and less energetic than those possessed by 

 the healthy adult. It is an important func- 

 tion of the mother to transfer to the suck- 

 ling through her milk immunizing bodies, 

 and the infant's stomach has the capacity, 

 which is afterwards lost, of absorbing these 

 substances in an active state. The relative 

 richness of the suckling's blood in protec- 

 tive antibodies, as contrasted with the arti- 

 ficially-fed infant, explains the greater 

 freedom of the former from infectious dis- 

 eases. 



The important question of the influence 

 of preexistent disease in predisposing to in- 

 fection has been brought nearer to a solu- 

 tion by recent studies of immunity. 

 Sehiitze and Scheller* have demonstrated 

 that, while the normal rabbit promptly re- 

 generates the complements used up in con- 

 sequence of the injection of hiemolytic 

 serum, a rabbit infected with the hog 

 cholera bacilhis has lost this capacity. My 

 former pupil. Dr. Longcope, has kindly 

 placed at my disposal the unpublished re- 

 sults of an investigation which he is mak- 

 ing under Professor Flexner's direction at 

 the Pennsylvania Hospital of the inter- 

 mediary bodies and the complements in 

 human blood in different diseases. Colon 

 and typhoid bacilli are used as the tests, 

 as, unless one accepts Bordet's doctrine of 

 the unity of complements, it is more im- 

 portant for the study of problems of in- 

 fection to determine bacteriolytic rather 



* Sehiitze and Seheller, Zeitschrift fiir Hygiene, 

 1901, XXXVI,, pp. 270 and 459. 



than hffimolytie antibodies. One of the 

 earliest results of the systematic bacterio- 

 logical examinations which we make at all 

 necropsies at the Johns Hopkins Hospital 

 was the recognition of the great frequency 

 of terminal infections, formerly often un- 

 detected by the clinician, in chronic dis- 

 eases, particularly of the heart, the blood 

 vessels, and the kidneys. Dr. Longcope 

 finds, although not regularly, still in many 

 cases of these diseases a marked reduction 

 in the quantity of complements, which 

 may amount to a total loss of the colon 

 complements. The analysis of the cases 

 brings out unmistakably a definite I'elation 

 between this loss of complement and the 

 predisposition to infection. 



The study of a series of acute infections, 

 chiefly of a surgical nature, shows that in 

 the course of the infection complements 

 are being constantly used up and regen- 

 erated, and that at any given time there 

 may be an excess or a reduction of the bac- 

 teriolytic power of the blood. Thus far it 

 has been found impossible in these acute 

 infections to attach any prognostic signi- 

 ficance to the amount of comiDlement or of 

 bacteriolytic power, nor could any definite 

 relation be determined between the leu- 

 cocyte count and the content of comple- 

 ments. 



Although we have traversed, gentlemen, 

 in this lecture a path which I fear has 

 seemed to you a long and winding one, 

 I am conscious that I have been able to 

 point out the features of the prospect only 

 imperfectly and incompletely. The ex- 

 tent and the richness in details have been 

 embarrassing. I trust, however, that I 

 have been able to indicate in some measure 

 the great interest and importance to biol- 

 ology, to physiology, to pathology, to every 

 department of medical science and art of 

 investigations which have led to a deeper 

 insight into certain manifestations of cell- 

 ular life. What has been conquered by 



