August Weismann

Experiments on the inheritance of mutilation

The
idea that germline cells contain information that passes to each
generation unaffected by experience and independent of the somatic
(body) cells, came to be referred to as the Weismann barrier, and is frequently quoted as putting a final end to the theory of Lamarck
and the inheritance of acquired characteristics. What Lamarck claimed
was the inheritance of characteristics acquired through effort, or will.

Weismann conducted the experiment of removing the tails of 68
white mice, repeatedly over 5 generations, and reporting that no mice
were born in consequence without a tail or even with a shorter tail. He
stated that "901 young were produced by five generations of artificially
mutilated parents, and yet there was not a single example of a
rudimentary tail or of any other abnormality in this organ."^[12]
Weismann was aware of the limitations of this experiment, and made it
clear that he embarked on the experiment precisely because, at the time,
there were many claims of animals inheriting mutilations (he refers to a
claim regarding a cat that had lost its tail having numerous tail-less
offspring). There were also claims of Jews born without foreskins. None
of these claims, he said, were backed up by reliable evidence that the
parent had in fact been mutilated, leaving the perfectly plausible
possibility that the modified offspring were the result of a mutated
gene. The purpose of his experiment was to lay the claims of inherited mutilation to rest. The results were consistent with Weismann's germ plasm theory.

August Weismann

Experiments on the inheritance of mutilation

The
idea that germline cells contain information that passes to each
generation unaffected by experience and independent of the somatic
(body) cells, came to be referred to as the Weismann barrier, and is frequently quoted as putting a final end to the theory of Lamarck
and the inheritance of acquired characteristics. What Lamarck claimed
was the inheritance of characteristics acquired through effort, or will.

Weismann conducted the experiment of removing the tails of 68
white mice, repeatedly over 5 generations, and reporting that no mice
were born in consequence without a tail or even with a shorter tail. He
stated that "901 young were produced by five generations of artificially
mutilated parents, and yet there was not a single example of a
rudimentary tail or of any other abnormality in this organ."^[12]
Weismann was aware of the limitations of this experiment, and made it
clear that he embarked on the experiment precisely because, at the time,
there were many claims of animals inheriting mutilations (he refers to a
claim regarding a cat that had lost its tail having numerous tail-less
offspring). There were also claims of Jews born without foreskins. None
of these claims, he said, were backed up by reliable evidence that the
parent had in fact been mutilated, leaving the perfectly plausible
possibility that the modified offspring were the result of a mutated
gene. The purpose of his experiment was to lay the claims of inherited mutilation to rest. The results were consistent with Weismann's germ plasm theory.