546 TRANSACTIONS OF THE CANADIAN INSTITUTE. [Vol. VIII 
There is another class of disease in which the influence makes entirely 
for racial deterioration. ‘This class is illustrated well by malaria. In 
malaria we have an infectious disease to which man develops a tolerance, 
but no true immunity. As mentioned above, Koch was the first to show 
that the native populations in malarial districts are all infected with 
the malarial parasite, and this observation has been fully confirmed 
by other students of tropical disease. It is extremely likely that what 
has been described as an immunity in whites is merely a chronic infection 
with tolerance. In malarial regions in the tropics the infection is com- 
municated to the children as soon as they are born and it may persist 
throughout life. Recently an exceedingly interesting study of malaria 
and its effects upon the nations about the Mediterranean has been pub- 
lished by W. H. S. Jones, of the Perse School, Cambridge. In this he 
seeks to show that the decadence of Greece between 500—300 B.C., was 
due to the spread of malaria especially in Attica. Similarly he seeks to 
show that the Roman decadence at the beginning of the Christian Era 
was, in part at least, due to the spread of malaria. I have not time to 
go into the arguments which he uses, but at least he has succeeded in con- 
vincing such an eminent authority on malaria as Major Ross. And 
to-day we certainly know that a malaria infected district is one in which 
the people show low vitality with a mental dullness which is entirely 
the results of the poisons of the disease. It may be that the absence of 
diseases of the type of malaria is accountable for the higher civilizations, 
which have developed in the temperate zones. Malaria is perhaps only 
one of the disease factors which lead to the low evolutionary position 
of the African races. They are also infested with numerous other para- 
sites which lower their vitality. It is an interesting fact that the finest 
type of the African races have, like the Zulu, developed in the more tem- 
perate zones or, like the Masai, in the highlands. 
In his prefatory note to Mr. Jones’ work, Ronald Ross refers to the 
apathy and feebleness of the inhabitants of many Indian villages, which 
has often been observed and he suggests that it is due to the presence of 
parasitic worms, especially the blood-sucking Anchylostoma, which 
produces a very chronic type of anemia. This reference is interesting 
because the presence of this worm has been demonstrated over large areas 
of the Southern States and there seems no doubt that the laziness and 
apathy of the poor white of the south is due to the wide-spread existence 
of the anemia of anchylostomiasis.- Here we have a factor, which has 
been of the very greatest influence in retarding the development of a 
most important section of the Southern United States. 
I think I have ma‘e it clear that disease, and especially parasitic 
