'Well,'
said Holmes,
'when
I examined Julia Stoner's bed-
room, I saw the bell-rope and the ventilator. I saw they were both
false. Then I noticed the bed was fixed to the floor.
'And
I realised that something could pass through the ven-
tilator. It could travel down the bell-rope and land on the bed.
Immediately, I thought of a snake.
'Dr
Roylott had other strange animals from India. It would be
easy for him to have a snake as well.
'So
he kept it in his safe and fed it with milk. And every
night he put the snake through the ventilator. It went into his
stepdaughter's room and came down the rope. He knew that one
night it would bite the girl in the
bed.'