Somatic and Germinal Variations 
at birth is probably largely germinal. According 
to Weismann and the majority of zoologists, 
there is a fundamental difference between these 
germinal and somatic variations, in that the 
former tend to be inherited, while the latter are 
never inherited. Weismann believes that very 
early in the formation of the embryo the cells 
which will form the generative organs of the 
developing organism are separated off from those 
cells which will go to build up the body, and 
become as much isolated from them as if they 
were contained in a hermetically-sealed flask, so 
that they remain totally unaffected by any 
changes which the environment effects in the 
somatic cells. Therefore, says Weismann, 
acquired characters cannot be inherited. 
While the majority of zoologists believe that 
acquired characters are not inherited, probably 
not many will go so far as Weismann and 
declare that the environment cannot exercise 
any effect whatever on the germ cells. 
Even though acquired characters or variations 
are not inherited, it does not follow that they do 
not play an important part in evolution. Acquired 
variations are the result of the way in which an 
organism reacts to its environment. If an organ- 
ism is unable to react to its environment it must 
inevitably perish. If it is able to react, it matters 
not, so far as the chances of survival of the 
organism are concerned, whether the adaptation 
; 107 
