BOOLOGICAL DISTRIBUTION OF DISEASE. 273 
up of round cells, with larger ones known as leprous cells 
intermixed. When suitably stained the nodules are 
found to contain enormous numbers of bacilli, many of 
which crowd the large leprous cells. 
It should be borne in mind that in the Mosaic books the 
term leprosy is used in a generic sense, for it included 
many forms of curable skin disease under this name, as a 
careful perusal of that very interesting chapter (Leviticus 
xiii.) will clearly show. It was only by isolating and 
carefully watching the initial red spots that a confident 
opinion could be expressed. The evidence furnished by 
the same chapter indicates that even when the disease 
was well pronounced, other affections than that which 
we now recognize as Elephantiasis grecorum were classed 
together under the term leprosy, but leprosy in animals 
is not mentioned once in the whole Pentateuch. 
The means described in the Mosaic books of isola- 
ting suspected cases, and allowing time to settle the 
diagnosis, are admirable. Even in these days of 
advanced civilization well-trained and _ thoughtful 
physicians find that the isolation of infectious cases 
is the best preventative treatment known. It is more 
than probable that this old-established custom explains 
the present restriction of leprosy to definite regions, such 
as Norway, Finland, and the Baltic provinces of Russia, 
Central and Southern America, South Africa, and 
Asia. 
As far as our knowledge of the zoological distribution 
of disease at present extends there are two affections 
peculiar to mankind, viz., true leprosy and syphilis. Even 
mental affections occur in animals: we have already 
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