786 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
discussion on tliis subject, the Organizing Committee had reminded the 
Section that the great amount of interesting work which had recently 
been done on the subject had one point in common — namely, the attenua- 
tion of virus, and preventive inoculation, the two subjects with which 
M. Pasteur’s name would for all time be honourably associated. With 
the single notable exception of vaccination, the only way of conferring 
immunity against any disease was the inoculation of the virus of the 
disease. To the old dangerous method of producing immunity by 
inoculation Pasteur had added the less dangerous one of preventive 
inoculation by means of an attenuated virus, to which he had applied 
the term vaccination. The designation “ attenuated ” virus ought to 
be reserved for virus weakened without being attenuated — for example, 
by artificially lowering' the vitality of the organisms for producing it. 
Methods of Attenuation . — Two methods of attenuation had been 
described by M. Pasteur — namely, the prolonged exposure of a culture 
to air at a suitable temperature, and the passage of the micro-organisms 
through the bodies of different species of animals. Other methods had 
also been employed — for example, the action of heat, the use of anti- 
septics, of compressed oxygen and light. 
In all cases, whatever the method employed, it was found to bo 
necessary that the attenuation should be effected slowly and gradually ; 
rapid attenuation rendered a virus altogether inactive without impres- 
sing on it any hereditary weakness. In whatever way the virus was 
prepared, it must, in order to confer immunity, be brought into direct 
contact with the tissues of the animal. In the early experiments the 
virus employed was always living ; the living microbe, itself attenuated 
as to its virulence, was used. Another possible method of conferring 
immunity was the inoculation of the chemical substances produced by 
the micro-organisms. 
Phagocytosis. — Dr. Poux next dealt with the doctrine of phagocytosis 
associated with the name of Dr. Metschnikoff. This observer had proved, by 
the study of the amoeboid movement of certain cells, that they possessed 
the power of including other cells and bodies in their substance. The 
phagocyte cells originated in the mesoderm. They possessed, further, 
the property of being able to digest the bodies which they had ingested. 
They were, in fact, the only cells which manifested in the human body 
any intracellular digestion. If the history of a bacterium in the interior 
of a phagocyte were followed, it would be seen that it underwent a 
peculiar series of alterations, very different from what took place when 
a microbe died in cultivating fluids. Whether a virulent virus was 
introduced into the bodies of animals which resisted inoculation, or 
whether attenuated microbes were injected into sensitive animals, the 
greater the degree of refractoriness shown by the animal, the more 
rapidly the microbes were consumed by the leucocytes. In a non- 
resistant animal the microbes remained free ; no such phenomenon as 
phagocytosis could be observed. It seemed, therefore, that the phago- 
cytes were charged with the defence of the human organism, and entered 
into conflict with the parasites which infected the human frame. It might 
be said that there were diseases in which the microbes were to be met 
with in the cells specially, and that these microbes nevertheless proved 
fatal to the animal. In tuberculosis and in leprosy the bacilli were to 
