"Medical Log, Stardate 4211.8. Kirk is right about the people here. Despite their fear and our strangeness, they're compassionate and gentle. I've learned the hunter Tyree is now their leader. He is expected to return shortly with his wife, who they say know show to cure this poison. My problem: the captain is in deep shock. I must keep him warm and alive until then." (TOS: "A Private Little War")
"Medical Log, Stardate 4770.3. Do I list one death or two? When Kirk's body died, Sargon was too far distant from his receptacle to transfer back. Sargon is dead. But is Captain Kirk dead? His body is, but his consciousness is still in the receptacle into which it was transferred earlier."
"Enterprise Medical Log, Stardate 5027.3. Dr. Leonard McCoy recording. I'm concerned about Captain Kirk. He shows indications of increasing tension and emotional stress. I can find no reason for the captain's behavior, except, possibly, that we've been on patrol too long without relief and diversion. He's resisted all my attempts to run a psychological profile on him."
"Medical Log, Stardate 5506.2. Captain Kirk and First Officer Spock were rescued 48 hours ago. They have no recollection of what happened to them after they were attacked, but medical examinations show an unidentified substance in the blood stream has affected their entire metabolism and changed them into water-breathers. Their internal structure is completely transformed, and even their eyes are covered with a transparent film, like the second eyelid of a fish. So far all efforts to return them to normal have failed."
"We have prepared an antitoxin from the venom of the sur-snake, but a part of the old records is missing, so the exact dosage is unknown. Experiments on fish show that if the antitoxin is too strong, it causes over-mutation, which cannot be reversed by any means. We are running out of venom, so conclusive experiments are impossible." (TAS: "The Ambergris Element")