IRK: Bones, how is he?
MCCOY: As far as I can tell from instrument readings, our prime suspect has a malfunction in one of the heart valve. It's similar to a heart attack in a human. But with Vulcan physiology, it's impossible to tell without an operation. Mrs. Sarek, has he had any previous attacks?
AMANDA: No.
SAREK: Yes. There were three others. My physician prescribed Benjisidrine for the condition.
AMANDA: Why didn't you tell me?
SAREK: There was nothing you could have done.
KIRK: Ambassador, when did you have these attacks?
SAREK: Two before we left Vulcan, the third a few hours ago. I was on the observation deck. When the Tellarite was murdered, I was quite incapacitated.
KIRK: There were no witnesses?
SAREK: None.
SPOCK: Doctor, do you propose surgery for the heart defect?
MCCOY: I'm not sure. It's tough enough on a human. On a Vulcan, an ordinary operation's out of the question.
KIRK: Why?
SAREK: Because of the construction of the Vulcan heart.
SPOCK: I suggest that a cryogenic open-heart procedure would be the logical approach.
SAREK: Yes, unquestionably.
KIRK: Bones, what about it?
MCCOY: Well, I'm glad somebody's asking me something around here. Well, the procedure they're discussing would require tremendous amounts of blood for the patient.
CHAPEL: Doctor?
MCCOY: Yes.
CHAPEL: I've checked the blood bank. There isn't enough Vulcan blood and plasma to even begin such an operation of this type.
KIRK: There are other Vulcans aboard.
SAREK: My blood type is T-negative. Somewhat rare, even for a Vulcan.
MCCOY: Yes, I'd say that's rare.
SPOCK: My blood is T-negative, Doctor.
CHAPEL: We've run a number of blood tests on Mister Spock. It isn't true Vulcan blood either. It has human blood elements in it.
SPOCK: It should be possible to filter out the human factors.
MCCOY: Even you couldn't give that much blood, Spock. It would kill you.
KIRK: Bones.
MCCOY: Mrs. Sarek, you must understand the chances are extremely small to find a way to produce sufficient T-negative blood.
SPOCK: Indeed. I would estimate the odds
AMANDA: Please don't.