510 
S. WOLFFBERG. 
exact details of the above experiments. So far as we in Ger¬ 
many are concerned, our knowledge of these is based only upon 
the above communication. 
We are therefore justified in looking upon them not only with 
some degree of wonder, but doubt also. 
Y. Frisch has the honor of having repeated some of M. Pas¬ 
teur’s experiments which bear upon the above assertion, and has 
come to the result “ that neither rabbits nor dogs can secure im¬ 
munity against the outbreak of rabies by the employment of M. 
Pasteur’s preventive treatment , when infection has already taken 
place through the intra-cranial introduction of rabid material .” 
It must be admitted, however, that these experiments do not 
satisfactorily nullify the assertions of M. Pasteur. 
If we consider the conditions by which protective inoculation 
with a mitigated virus is to prevent the outbreak of rabies after 
an animal (man) has already been bitten by a rabid dog, we must, 
a priori, assume that the changes produced by the inoculation 
have either run their course or attained a high degree of devel¬ 
opment before the virus introduced by the bite has developed any 
considerable degree of activity: Hence, the protecting disease 
must have an essentially shorter course than the natural rabies. 
So far as rabies in man is concerned, it is assumed that forty 
to sixty days must generally elapse, from the time the person was 
bitten by a rabid dog, before the phenomena of the disease 
appear. During this so-called period of incubation of forty to 
sixty days, it cannot be assumed that the infecting elements lie 
entirely dormant; they undoubtedly increase and disperse them¬ 
selves, so that, from the period of infection to the outbreak of 
the disease, their generalization over the organism must gradually 
take place. 
It is, therefore, of the utmost importance, for the successful 
action of the inoculation which follows the biting of an individ¬ 
ual, to determine the length of time subsequent to the same in 
which the same can be resorted to; that is, the difference in the 
period of incubation (better generalization—B.) between the arti¬ 
ficial and natural disease. 
Herein is to be sought the vital point in the experiments and 
new discoveries of M. Pasteur for the prevention of rabies. 
