1014 | | Zoic Maxima, or Periods of [ December, 
agencies of the surface, and increase their likelihood of fecunda- 
tion by the longer possible period thus secured for a greater 
number, 
Such fish as spawn in rivers or in the later seasons, as early 
summer, may be in some instances, or most, more likely to per- 
petuate a greater number of offspring than their congeners whose 
eggs in the ocean are exposed to greater risks of destruction or 
at seasons when storms are prevalent, though this consideration 
is again modified by the possible presence in either case of more 
numerous enemies. 
Ti. Constitution, rate of growth, habits, etc., of an organism — 
It is obvious that conditions favorable for the preservation and 
maturization of individuals will prevail when these conditions 
harmonize with the habit and life-history of the organism, and 
that the reverse will ensue when they do not, and other things 
being equal we may expect those species to predominate at a 
locality whose habits, life-history, etc., are either best adapted to 
the conditions of that locality over its competitors, or are of such 
a character as to withstand conditions which, generally unfavora- 
ble to all forms of life, are met by it with better safeguards and 
greater resistance, 
Under unfavorable conditions the longer time in which the 
young of a marine shell are free before attachment, the less 
chance for a survival of a great number, and at such a time a 
selection would be effected in favor of those species whose spat 
most quickly came to rest, and these would subsequently become 
phenomenally frequent. ' 
\gain, the power of an organism to endure change of temper 
ature, as compared with others less able to survive variation in 
this respect, obviously works in its favor, and may lead to go 
apparent excess of individuals. As Semper says,’ “a small fali 
-in temperature may be as injurious to one animal as a great fall 
_ to another, while a third species may be wholly unaffected by 
either.” Mdébius has designated animals under this regard as 
_ eurythermal and stenothermal, as they are qualified to endure 
, : _ reat or small variations of temperature. This will also have ” 
_ important influence on size, as Möbius has shown that the sa 
species of mollusk living on the coast of Greenland or in the Bal- 
tic was in the former case large, in the latter dwarfed, and he at- 
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