174 BULLETIN OF WISCONSIN NATURAL HISTORY SOCIETY. VOL. 3, NO. 4. 
crease of the animal due to the hospitality would introduce a 
feature of hostility. The often calculated results of the un- 
checked increase of even the slowest breeding animals show how 
quickly the possibilities of the hospitable environment would be 
taxed and the very number of individuals would introduce the 
factor of passive hostility among animals of the same species. 
Moreover the increase in numbers would afford the most hospi- 
table field for the development of predatory habits, or the con- 
centrated attacks of hostile factors, as wolves follow herds of deer 
or buffalo, or diseases attack communities of plants or animals. 
Environmental hospitality presents two other phases. 1. 
Environmental diversity. 2. Environmental monotony. In the 
first the sum of favorable contacts includes a great variety of 
factors as variable climate, diversified surface, complex food sup- 
ply, etc. The second would be the reverse of this, a simple climate 
with monotonous surface and simple food supply, such a condi- 
tion would obtain in the deeper ocean or lake waters, the surface 
of an ocean or lake far from the shores or the surface of a large 
plain, plateau or desert. 
It is readily seen that a region might be diverse to one form 
and monotonous to another as a plain might have a variable 
climate which would be of importance to one form and indiffer- 
ent to another while the other factors were in common. The 
two conditions, environmental diversity and monotony would re- 
sult very differently. In the first the diversity would render it 
more probable that varieites would find a favorable sum of con- 
tacts and so become permanent as species while it would at the 
same time indefinitely postpone the approach of passive hostility 
among the individuals for the varieties though more liable to ex- 
tinction than in a condition of environmental hostility would be 
less liable than in a condition of environmental monotony. 
On the other hand animals developing in a condition of en- 
vironmental monotony would soon arrive at a condition of over- 
crowding and passive hostility among the individuals, for the 
poverty of the environment would place the varieties even in their 
inception in a condition of hostility while those which bred true 
to the parent would experience hospitality and survive ; the re- 
sult would be large numbers of individuals of the same species. 
A good example of this is where animals essentially terrestrial 
have passed over to an aquatic habit, as the marine reptiles ; they 
are limited in the number of genera and species far beyond the 
land reptiles. As the varieties would constantly fail and the in- 
dividuals increase passive hostility would soon supervene and the 
