THE MICROBES OF HUMAN DISEASES. 223 
is an attenuated form of small-pox. The same treat- 
ment applies to both diseases. When the patient is 
kept in the purifying chamber of a gas manufactory, 
where there is a constant disengagement of acid 
vapours, sulphuretted hydrogen, hydro-carbons, coal 
tar, benzine, carbolic acid, etc., the microbes embedded 
in the throat and lungs are attenuated. Sulphate of 
calcium is a successful remedy in whooping-cough as 
well as in croup. 
Children who have had whooping-cough, or who 
are passing through the disease, rarely contract croup 
even when it is epidemic, although catarrh, inflamma- 
tion of the bronchial tubes, ulceration of the mouth, 
and general debility, are all predisposing causes of 
croup. The question therefore arises whether whoop- 
ing-cough does not act as a sort of preventive vaccina- 
tion which may serve as a protection against croup. 
Further researches and observations should be made 
in this direction, if that which we now indicate can 
be established as a fact. 
XI, Tot MicroBes oF PHTHISIS AND OF LEPROSY. 
These two microbes are so similar in form that it 
is necessary to have recourse to chemical reagents and 
to staining processes in order to distinguish them 
clearly. Both assume the form of an 8, or of slender, 
elongated rods, so minute that it is not surprising 
