SCIENCE. 



[X. S. Vol. XVUI. Xu. 444. 



pathology, of recent acquisition and some- 

 what obscure nature, possessed by the as- 

 surance that my audience can afford to 

 dispense with an explanatory introduction 

 because of its acquaintance with the newer 

 facts of immunity in relation to pathology, 

 so brilliantly dealt with in Professor 

 Welch's Huxley lecture. 



So many pathological phenomena have, 

 in the past, been attributed to alterations 

 of the blood, and recent discovery has 

 added so largely to the list of the activities 

 ■of this fluid, that one is tempted, as he 

 views the wonderful properties with which 

 it is endowed, to exclaim with Goethe : ' Das 

 Blut ist ein ganz besonderes Saft.' The 

 manner of the solution of blood corpuscles 

 brought aboiit by alien serum is a well- 

 ]mown phenomenon that many years since, 

 through the studies of Landois and others, 

 was made to explain the unsuccessful and 

 even disastrous effects of blood transfusion. 

 More recent investigations have shown that 

 by a process akin to artificial immuniza- 

 tion to bacteria, a similar but more intense 

 capacity of bringing about solution of 

 blood corpuscles can be developed in blood 

 serums which naturally do not possess this 

 action, and increase of the power can be 

 produced in serums in which it is already 

 present. 



This solution consists in the liberation 

 of hfemoglobin from the stroma of red cor- 

 puscles and its diffusion through the fluid, 

 a process to which the name 'haemolysis' 

 has been given. Careful observation of 

 this phenomenon has shown that, in many 

 cases, a state of coalescence of the cor- 

 puscles, to which the name 'agglutination' 

 is applied, precedes that of solution; and, 

 further, that while these changes are often 

 associated, yet one may occur in the ab- 

 sence of the other. 



While, under normal conditions, the 

 serum of an animal is without injurioi^s 



action upon the corpuscles suspended in it, 

 yet in certain pathological states the serum 

 suffers an alteration through which its cor- 

 puscles are acted upon injuriously, are 

 made to agglutinate, and even to undergo 

 complete dissolution. Coincident with the 

 appearance of this activity, it often hap- 

 pens that the serum has acquired increased 

 power of solution over corpuscles of a for- 

 eign nature ; and this alteration in proper- 

 ties acquired by the serum is held respon- 

 sible for the blood destruction that accom- 

 panies manj' of the infectious diseases, and 

 is so apparent and serious a condition in 

 certain diseases — e. g., severe anaemias, the 

 causation of which is still unknown. 



In view of the acquisition of such new 

 and hurtful qualities by the blood serum, 

 the discovery in cultures of many kinds of 

 pathogenic bacteria of hremolytic and ag- 

 glutinating substances for red corpuscles 

 is a peculiarly welcome addition to our 

 knowledge of blood destruction in disease. 

 And while this Imowledge has not led to 

 the understanding of all forms of blood 

 destruction, and has as yet failed to shed 

 important light upon certain clinical types 

 of severe and pernicious antemia, we have 

 obtained a new standpoint from which to 

 view the so-called blood diseases that prom- 

 ises further progress in the near future. 



It is common experience in science to 

 find that accurate observation has preceded 

 adequate explanation. The manner of ac- 

 tion of bacterial agents upon red corpus- 

 cles, and our recently acquired knowledge 

 of agglutination of cells in general, could 

 not fail to suggest that certain kinds of 

 thrombi are produced by a form of coales- 

 cence of corpuscles; and I was not, there- 

 fore, surprised to find unmistakable evi- 

 dences of agglutination of red corpuscles 

 in the blood vessels of the intestine and 

 other organs in typhoid fever, in the lung 

 in lobular pneumonia, and in some other 



