Santa's conclusion

Santa Singh is in a dissection class of cockroach.
He cuts its 1 leg, and says, "walk", it walks.

He cuts 2nd and 3rd legs and said, "walk" , it walks.
He cuts all the legs and said, "walk...."

Finally he wrote the conclusion.. ....
..... "after all the legs of a cockroach are cut - it becomes deaf......"