ADDRESS. 27 



that of Bucliner ' on the chemical excitability of leucocytes being 

 among the most important. Mnch discussion has taken place, as many 

 present are aware, as to the kind of wandering cells, or leucocytes, 

 which in the first instance attack morbific microbes, and how they deal 

 with them. The question is not by any means decided. It has, however, 

 I venture to think, been conclusively shown that the process of destruc- 

 tion is a chemical one, that the destructive agent has its source in the 

 chemiotactic cells — that is, cells which act under the orders of chemical 

 stimuli. Two Cambridge observers, Messrs. Kanthack and Hardy,- have 

 lately shown that, in the particular instance which they have investigated, 

 the cells which are most directly concerned in the destruction of morbific 

 bacilli, aUhough chemiotactic, do not possess the power of incorporating 

 either bacilli or particles of any other kind. While, therefore, we must 

 regard the relation between the process of devitalising and that of 

 incorporating as not yet sufficiently determined, it is now no longer 

 possible to regard the latter as essential to the former. 



There seems, therefore, to be very little doubt that chemiotactic cells are 

 among the agents by which the human or animal organism protects itself 

 against infection. There are, however, many questions connected with 

 this action which have not yet been answered. The first of these are 

 chemical ones — that of the nature of the attractive substance and that 

 of the process by which the living carriers of infection are destroyed. 

 Another point to be determined is how far the process admits of adapta- 

 tion to the pai'ticular infection which is present in each case, and to the 

 state of liability or immunity of the infected individual. The subject is 

 therefore of great complication. None of the points I have suggested 

 can be settled by experiments in glass tubes such as I have described to 

 you. These serve only as indications of the course to be followed in 

 much more complicated and difficult investigations — when we have to do 

 with acute diseases as they actually afiTect ourselves or animals of similar 

 liabilities to ourselves, and find ourselves face to face with the question 

 of their causes. 



It is possible that many members of the Association are not aware of 

 the unfavourable — I will not say discreditable — position that this country 

 at present occupies in relation to the scientific study of this great sub- 

 ject — the causes and mode of prevention of infectious diseases. As 

 regards administrative efficiency in matters relating to public health 

 England was at one time far ahead of all other countries, and still re- 

 tains its superiority ; but as regards scientific knowledge we are, in this 

 subject as in others, content to borrow from our neighbours. Ihose who 

 desire either to learn the methods of research or to carry out scientific 



' Buchner, 'Die chem. Reizbarkeit der liencocyten,' Sec, Berlitier Mi ii. Wuok., 1890^ 

 1^0. 17. 



^ Kanthack and Hardy, ' On the Characters and Behaviour of the Wandering Cells- 

 of the Frog,' Proceedings of the Boyal Society, vol. lii. p. 267. 



