Ill 



any tribe of bacteria, even if " only micrococci." There 

 are micrococci and micrococci. 



Again, it is said, how is it possible for recovery to oc- 

 cur from a disease caused by bacteria ? What stops 

 their growth ? So far as I am aware, this question has 

 not been decisively answered. Several facts suggest that 

 the products of their own vital activity arrest further de- 

 velopment. Analogous facts have been demonstrated : 

 the mucoj racemosus ceases to grow in a liquid when 

 the alcohol produced by its own vital action exceeds a 

 certain percentage, though there may still remain fer- 

 mentable sugar in abundance. During putrefaction 

 there are produced numerous compounds, of which one 

 at least, carbolic acid, arrests, even in small quantities, 

 further development of putrefactive bacteria. Brieger 

 has recently shown that the infectious diseases proven 

 clinically and experimentally to be caused by putrid in- 

 fection pyaemia, diphtheria, erysipelas are distin- 

 guished by the excretion in the urine of excessive quan- 

 tities of carbolic acid ; while in other diseases exhibiting 

 equally intense fever and constitutional disturbance 

 acute rheumatism and variola, for example the amount 

 of this acid in the urine is normal or subnormal. Hence 

 the conjecture that the bacteria are both bane and anti- 

 dote. Yet a failure to explain the phenomena satisfac- 

 torily does not, of course, impair the stability of the fact. 

 The bacilli of anthrax are observed to become, in the 

 living animal, pale, of uneven outline, incapable of ab- 

 sorbing staining fluids ; in short, they are dead. With 

 their death the convalescence of the host begins, as a 

 rule. 



It should be remembered that other parasites than bac- 

 teria may cause disease, some of them, perhaps, over- 

 looked in the universal hunt .after bacteria. Koch calls 

 attention to Woronin's discovery that a disease of cab- 

 bages is caused by an amoeboid parasite, which enters the 

 root of the plant and becomes almost indistinguishable 

 from the proper vegetable cells ; and suggests the possi- 

 bility that some of the amoeboid bodies known as white 



