Second Scientist

The Second Scientist was a Sensorite scientist, who worked with his senior colleague to cure John of the madness caused by the Sensorites' telepathic attacks on his mind.

Biography
The scientist and his senior colleague were recognised by a swirling pattern insignia on their chests.

They later helped the First Doctor test the water on the Sense Sphere for poison, specifically atropine. When the scientists found the poison, they helped the Doctor to develop an antidote. (TV: The Sensorites)