koch’s method with tuberculosis. 
83 
feed the microbe; by the deposition in the tissues of poisons 
inimical to the microbe, and of condensation of the lymph 
channels and glands, the first two being contradicted by the 
growth of the bacteria in the bouillon made from the flesh of 
an insusceptible animal, and their growth in a flask charged 
with their chemical products, provided fresh meat infusion is 
introduced. The third theory is disproved by the fact, that 
different bacteridian diseases, all alike resulting in such con- - 
densation of lymph channels, are not mutually vicarious of 
each other.. The doctrine of physiological resistance is shown 
to agree with all the facts and the immunity of the calf whose 
dam has passed through the bacteridian disease in the latter 
period of the gestation is especially dwelt on as evidence. 
“ This view is further strengthened by the fact that though 
an animal that has acquired an immunity from a specific dis¬ 
ease, afterward produces offspring which are susceptible 
to the disease in question, yet it has. been shown in the case 
of anthrax that, if such immunity on the part of the parent 
has been acquired by a non-fatal attack of the affection during 
advanced pregnancy, the preservative effect is extended to 
the foetus as well. Here the foetus has advanced beyond the 
condition of an ovum, or of simple embryonic cells or tissues, 
and is already well formed, with all its differential bones, 
muscles, tendons, brain, nerves, vessels and viscera. The 
nuclei presiding over the growth of these different structures 
are henceforth fixed in their powers, and any habitude im¬ 
pressed upon them may now be permanently preserved just 
as it is in the adult animal. 
“ This consideration serves to fortify the doctrine that the 
immunity from a contagious disease acquired by. a first attack 
is due to a habit, or acquired powers of endurance or resistance 
on the part of the living cells or nuclei of the animal body. 
This better accords with and explains observed facts, and is 
liable to fewer objections than any theory that has come 
under our notice. * * * 
“ To return to our question. Do the observed facts ac¬ 
cord best with the idea that protection is acquired by the 
action of the chemical products only of the bacteria, or is the 
